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MINISTRY OF CULTURE AND SPORTGENERAL DIRECTORATE OF ANTIQUITIES AND CULTURAL HERITAGEDIRECTORATE OF MUSEUMS / DEPARTMENT OF EDUCATIONAL PROGRAMS AND COMMUNICATION

... ABOUT THE CAUSES BEHIND THE DESTRUCTION OF SCULPTURES AND ARCHITECTURAL MONUMENTS

Preventive

conservation:

a shield that

protects

monuments

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Damage to sculptures and architectural monuments is due, on the one hand,

to the materials from which they are made and, on the other hand, to reasons

relating to their environment, some natural others due to human intervention.

... is utilised to construct monuments, whether these are buildings or

small works of art. Until recently, people mainly chose durable natural

materials that could be found in their nearby surroundings. Stones and

metals from their land, wood from their forests, ceramics, glass, mortars

and colorants made of local soil. On rare occasions artisans chose more

precious materials, which they transported from far away.

Porous rock from Piraeus, grey limestone from Eleusina,

and Pentelic marble were all utilised in the

foundations of the Propylaea of the Athens Acropolis.

Various rocks, ceramics and mortars were utilised to construct the church of Agioi Theodoroi at Mystras.

With the passage of time, however, technology developed and materials

were transported and ideas transmitted, so we now find ever more frequently

new materials in monuments, materials such as metal alloys or mortars

or different kinds of plastic with greater durability and more creative

possibilities.

You can see sculptures by Greek sculptors from the 20th century and the dawn of the 21st century in the webpages of the Greek National Glyptotheke (Sculpture Gallery):

• http://www.nationalgallery.gr/site/content.php?sel=690&artwork_id=73270

• http://www.nationalgallery.gr/site/content.php?sel=677&artwork_id=75364

A. A great variety of materials …

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... about the causes of destruction of sculptures and architectural monuments

http://www.nationalgallery.gr/site/content.php?sel=677&artwork_id=75364

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Today, in the arts, many artists try out a variety of materials in their art,

materials that inspire them due to colour, texture, shape or… the idea they

represent, such as chocolate, coloured medicine capsules and so forth.

The various materials utilised in a monument aren’t all destroyed at the

same pace. The rate at which each material is destroyed has to do with:

- its composition, i.e. the ingredients of which it is made and

- its structure, i.e. if it is hard or soft, if it has large or small pores and so forth.

• http://www.bbc.co.uk/wiltshire/content/image_galleries/wiltshire_06_year_in_pixs_gallery.shtml?14

• http://www.pharmacopoeia-art.net/artworks

Consequently, different materials, depending on their composition and their

structure, are more or less resilient to pressure, or earthquakes; they absorb

more or less water; they are attacked by microorganisms with greater or

lesser ease; they rust or fade faster or slower under the sun. For example,

wood is destroyed faster than marble and iron rusts faster than titanium.

In the same environment, the structural rock which

was used to build the Tower of London

is less resilient to water and salts than the mortar used.

The soft material of the veins in the marble used on Hadrian’s Arch eroded far faster than the marble, leaving gaps.

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... in other words, the environmental conditions that hold sway in the area

of the monument are jointly modulated by :

a) various natural factors that have to do with climate, distance from the

sea, altitude, the level of the water table and so forth.

b) human activity, on a local and a global scale.

No single cause is responsible in and of itself for the destruction of a material

or a monument.

The most fundamental causes and the manner in which these are connected

are :

Water is everywhere above and around the monuments as a liquid, a solid or a

gas and contributes to the destruction of their materials in many different ways:

B. The environment of monuments…

1. The destructive effect of water on the materials of sculptures and architectural monuments.

Water “dissolves”...

... almost all the substances on this planet, some more and some less,

and that’s why chemists call it a “universal solvent”. It also dissolves

the materials of monuments. How does that happen? The presence of water has always existed with monuments as with the Bridge of Arta.

Broken segments of the same column were preserved in a different environment and eroded differently.

Read about an unusual environment of an unusual monument:

• http://www.underwatersculpture.com/sculptures/process/

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Water molecules can easily insert themselves in between the atoms1 f other

molecules2 and dissolve3 all the minerals of the stone materials of monuments,

sometimes at a very rapid rate, sometimes at a slower rate. This is due to:

a) the polarity4 of water molecules;

b) heir ability to connect to each other using hydrogen bonds5.

Due to these two qualities, water in nature is never absolutely pure, as

it constantly dissolves, carries away and transports along with it various

substances it finds along its path, such as salts, metals, atmospheric or soil

pollutants, and much more. Often the substances that are dissolved in the

water can increase its solvent qualities even more.

The ability of ions and molecules to be dissolved by water, including sea salt, otherwise known as sodium chloride,

is due to the polarity of the water molecule © University of Arizona.

Crystal structure of NaCl NaCl in water

Positive charge

Hydrogen bond

Negative charge

Hydrogen

Oxygen

Hydrogen

1 atom: the smallest particle of a chemical element that maintains the chemical qualities of an element2 molecule: the smallest component of an element or compound that can exist in free form without losing the physical / chemical qualities of the element or compound. The atoms of a molecule can be of the same or different elements.3 dissolve: a chemical process by which a chemical substance, whether solid, liquid or gas,

liquid or gas, is fully cleaved into molecules or ions in another substance. 4 polarity of water molecules: the separation of their electrical charge, which results in their displaying a positive and a negative centre and renders them able to dissolve other polar compounds.5 hydrogen bonds: a form of attractive force between two molecules with some electrical charges of opposite polarity, where one is hydrogen. Hydrogen bonds are the reason why water is liquid at room temperature (20oC) in contrast with other chemical compounds, which are gaseous under the same temperatures.

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Now that I think of it, according to myth, the

water of the Styx, at Helmos in Achaia, was

considered to be able to melt any object made

by man whether it was made of glass, crystal,

morrine6, rock, clay, horn, bone, iron, copper,

lead, tin, silver or electron, but not of gold… It

wasn’t randomly that Thetis christened her son

Achilles in those waters to make him invulnerable.

The water was sourced from Tartarus of the un-

derworld and on it were sworn the oaths of the

gods… What dissolved substance could it be that

increased its solvent qualities? I never did learn…

Water “inflates/swells”

all the materials into which it enters. Remember the old wood

shutters that are so hard to open

and close after the rain; or the

wooden floors that creak? How

does that happen?

The waters of the sources at Lyncestes

had the reputation of dissolving stones…

stones in the bladder and the kidneys

and not those alone!

Vitruvius, today we call the water “Sour Water of Flo-

rina” and we know from chemical tests that its curative

properties are due to the abundant carbonic acid dissolved

in the water!

The water of the Styx at Helmos in Achaia now.

6 morrine: Pausanias refers to a mineral or vitreous material, which the Ancient Greeks and Romans utilised

to make durable and luxurious vessels.

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Water penetrates inside the material of monuments through rain, snow,

hail or frost, atmospheric humidity, ground humidity and the sea. It fills the

pores of materials and these “swell” and grow in dimensions, or to put it

more scientifically they expand. The accumulated

water presses and “stresses” the walls of these

pores7. In the meantime the materials swollen

by water press on those next to them.

When the temperature of the environment rises,

the water evaporates, the pores of the materials

empty, the materials deflate, “tighten”, compress

and approach their initial limits.

Regular repetition of the cycle of entrance/exit

from the pores “tires” their walls and ends up

breaking them. The size and number of pores and

microfissures increases, and so does the quantity

of water the material will absorb the next time,

while the durability of the materials lessens.

This is why, when you fill the ice cube tray with water, you can see later on that

the ice cubes “overflow”!

Correspondingly, in wintertime, when there is frost, the water contained in the

pores of the materials of monuments freezes, expands, presses and breaks the

walls of the pores.

Water “freezes”...

... at temperatures below 4oC,

whereupon its volume increases

by approximately 9%!

7 pores: he gaps that exist in solids.

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The frost problem is serious for monuments that are located in the mountains,

such as the Temple of Apollo Epicurious at Bassae in Figaleia, at 1130m., and

for those whose material was already wet inside when hit by frost, and so the

water in their pores froze and broke their walls.

In contrast, frost is far less of a threat to monuments

made of non porous stone and those that have the

good fortune to be located in places with a milder

climate, such as the monuments of the Athens

Acropolis, which are made of Pentelic marble.

This is because metals and their alloys are corroded8, in other words they

lose electrons from their outer shells, which are bound by the environmental

oxygen, which is dissolved in some form of electrolyte9, such as rainwater,

atmospheric humidity or damp from the sea. This creates compounds on their

surface in the form of coloured layers, known to us as rust.

The Temple of Apollo Epicurious at Bassae in Figaleia, at an altitude of 1,130m., with the cover that protects it from the frost.

This is why in the past, before winter settled in and

damp entered the rocks, we used to “polish” the joins

of stones on all exterior masonry with oil, in order

to insulate and protect them. As you know, oil and

water do not mix!

Water rusts ..

... metals in our homes and in our lives. Iron railings turn orange;

bronze door handles turn green; bicycle chains get “stuck”...

8 corrosion: a spontaneous chemical process by which a metal loses electrons from its outer shell,

which are usually taken up by oxygen in the environmentς. 9 electrolyte: any substance the aqueous solution of which provides freely moving ions and can carry an electric current.

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Metal corrosion is more rapid when there is increased humidity, i.e. water,

either by itself or with salt, airborne pollutants and other dissolved

substances. On the one hand, this is because metals come into contact with

more dissolved oxygen, on the other hand, because water dissolves and

removes the coloured products of corrosion from metal surfaces, revealing

new pure metal, which is then also available to be corroded. So monuments

made out of metal are constantly losing material, while they also undergo

mechanical damage. Outdoor monuments made out of alloys10 of brass or

bronze, that contain copper turn green, while iron parts and connections

on monuments turn “red” (“rust”) and stain the stones.

The existence of water on monuments is

responsible for corroding the metal parts and staining the stone.

The green corrosion of copper stains the monument of Vittorio Emanuele II in Rome.10 alloy: a mixture of two or more metals in order to combine and improve their qualities.

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Water is life!

The role of water is very significant

for the development of all living organisms,

as it makes up 70-90% of their cells!

The water that is absorbed by the materials

of monuments greatly encourages the growth

and action of destructive microbes, plants

and animals nearby, on and within the monuments.

This becomes particularly obvious at abandoned

monuments, where nature has the opportunity

to take back, in a manner of speaking, the place

that is hers by right.

The extended presence of water on monuments such as Hadrian’s Arch in Athens promotes the development of plants and microbes.

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Salt isn’t just what we eat…

... sodium chloride from the sea. Salts are a very widespread group

of chemical compounds that are all around us and even inside us!

Around and inside monuments.

Salts are natural components of certain minerals11, rocks12 and ores13,

such as gypsum, the calcium carbonate of marble or siderite and galen-

ite. Salts are also the main ingredients of the tissues14 of all living organ-

isms, such as calcium phosphate in the shells of shellfish and the bones of

vertebrates and humans. And, of course, there are many dissolved salts

to be found in water from springs, rivers, lakes and, particularly, the sea.

Salts reach monuments…

... along with water, particularly from the sea! Sea spray, rich in salts travels and “pollutes” monuments even those located many

kilometres from the shore. Other sources of salts are damp in the ground, but also the structural materials themselves, both stones

and mortars15. Salts also form on stone monuments due to their interaction with various atmospheric pollutants (e.g. the formation of

gypsum from the reaction of marble with sulfur oxides - “gypsymisation” or “sulphation”). We find salts on and in all monuments.

2. The destructive effect of salts on the materials of sculptures and architectural monuments

Where salts are? Everywhere!

On the beach of Stavros at Chania, when the sea water evaporates, the salts are crystallized in the recesses of the rocks at the ruins of the Venetian quarries.

11 mineral: chemical element or inorganic compound in the ground or water, which is solid at room temperature.12 rock: a natural material from the earth’s crust. It is made up of one or more minerals.13 ore: a material that is mined from the earth. It contains a significant quantity of a metal that is useful for humans.

14 tissue: a group of cells of a single organism which have similar structure and physiology.15 mortar: mixture of water and materials such as sand, lime, cement etc, utilised as binder in wall building / masonry.

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... because this is when the temperature in the environment rises, environ-

mental humidity is lower and the water inside stone and other porous ma-

terials of monuments (mortar, clay, wood and others) travels to the surface

in order to evaporate. Large salt crystals form on and below the surfaces of

stone materials in the form of white or light-coloured crust (bloom). The

crystals press upon and break the walls of the pores, creating fissures and

loss of stone material.

Salt bloom on the walls of the imperial monuments

on Palatine Hill in Rome.

Salt bloom on porous rock foundations in the Ancient Agora in Athens.

I’ve been saying it from the 1st century!

Never build walls using sea sand, because

their surface will very soon be destroyed

by a layer of salt.

Monument conservators fear the salts in spring…

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When the weather gets colder and atmospheric humidity starts to rise

again, the soluble salts on the stones are re-dissolved and move again to

the interior of materials, to find new positions in order to re-crystallize,

increasing their initial volume.

When the temperature and humidity of the environment see-saws

regularly and the cycle of salt crystallization is repeated more frequently,

the materials are stressed more and are more readily damaged by salts.

Often the damage from salts takes the form of small holes and is called

pitting erosion.

Pitting erosion of stones near the sea due to continuous cycles of crystallization and salt mobilisation.

Don’t use soft stone near the sea,

because the salt and the heat will melt them!

Prefer rocks like travertine, hard and porous,

which can hold up to salt as well as

they do bearing loads!

Disintegration and loss of structural material of the Tower of London due to blooming and salt crystallisation.

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Additionally, the capacity of salts to draw and retain humidity for

greater lengths of time inside rocks and porous materials (hygro-

scopicity) creates conditions that favour the growth and action of

plants and microorganisms and to the detriment of the monuments.

Salt hygroscopicity and their capacity to increase water conductivity16

are responsible for the accelerated corrosion of metal parts of

monuments. Sea salts accelerate corrosion due to humidity of the iron

cannon from the monument of the Battle of Crete at Sfakia, Chania.

Sea salts accelerate corrosion due to humidity of the iron cannon from the monument of the Battle of Crete at Sfakia, Chania.

16 conductivity: the capacity of a solution to conduct an electrical current. Solutions of most inorganic salts are relatively good electricity conductors.

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The wind destroys stone surfaces of monuments by blasting them with

dust and sand particles as well as particulate matter and removing from

these any material that is already damaged and ready to be lost.

Furthermore, the wind decreases relative humidity in the environment,

accelerating water evaporation and salt bloom and crystallization. The

result of wind action is a great loss of materials.

3. The destructive effect of the wind on materials of sculptures and architectural monuments.

The Sphinx at Giza in Egypt is constantly losing the features of its face due to the action of the wind and sand particles from the desert that fall on it with force.

The Naxian lions on the island of Delos lost the sculptured features of their faces due to the action of the wind and sea salts. This is why over the past few years they have been transported to the museum and copies have been placed in their stead.

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In Greek mythology the god Aeolus guarded the

nine winds in a sack and would free them according

to the instigation of Zeus, Poseidon or Athena.

Nowadays conservators call the destructive action

of the wind on the stone material of monuments

“aeolian” erosion.

Finally, we should mention that, in urban and industrial centres, wind

direction and speed play a defining role in formulating levels of airborne

pollutants.

Depiction of the transport and diffusion of pollution from the region of Eleusis, in western Attica, to the centre of Athens. Areas coloured green are more affected by the pollutant movement, and this, in turn, has an adverse effect on monuments.

Destruction from the winds

can be immense and

people often called upon

the help of the gods.

At Methoni the goddess Athena

was given the prosonym Anemotis

because she helped to calm

the strong winds in the region.

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The temperature of the environment of monuments is never stable.

It changes constantly during the day, the seasons and the year.

In spring and summer, temperature increases make the various materials

of monuments grown in all three dimensions, i.e. expand. This is because

they absorb heat from the environment, increasing their kinetic energy17

and the velocity of their molecules, and thus the distance between these.

Correspondingly, as it gets colder, the materials radiate heat and

contract, i.e. grow smaller in all their dimensions.

The constant contraction / expansion of materials causes “stress”.

Additionally, the various materials, that monuments are made of, have

different coefficients of thermal expansion and thus behave differently.

This makes them exert pressure on each other, creating fissures and loss

of material.

4. The destructive effect of changes in temperature on the materials of sculptures and architectural monuments.

Power cables in winter.

Power cables in summer.

17 Kinetic energy of molecules: he energy that molecules of a chemical substance have when they move. This refers to their ability to do work and depends on their mass and velocity.

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It makes sense, therefore,

to build our houses in harmony

with the climate of our land.

A house that is suitable for the climate

of Egypt won’t be suitable

for that of Spain, as one place is under

constant sun, while the other isn’t.

When there are many and abrupt changes

of temperature, as for example in instances

of frost or fire, the damage they cause to

materials is greater. For example there is

the damage caused to stones inside

the Erechtheion on the Acropolis, which is

due to a fire.

However, changes in temperature

are also linked to the damage caused to

monuments due to salts, while high

temperatures and humidity levels also

encourage the growth of plants and

microbles.

Houses in the Shiva Oasis, in Egypt.

Toledo, Spain, Puerta Bisagra.

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Why did our grandmother turn her laundry inside out to dry on the line?

Why do we wear glasses and sunscreen on the beach?

Διότι το φως του ήλιου είναι καταστρεπτικό για όλα τα οργανικά υλικά. Ξεβάφει

τα χρώματα των ρούχων μας και καταστρέφει τα μάτια και το δέρμα μας.

5. The destructive effect of changes in sun radiation on the materials of sculptures and architectural monuments.

Sun radiation is responsible for changing colours.

If you’re building your homes,

make sure that your picture galleries,

weaving rooms and painting studios face North,

as the light is more steady and it won’t affect

the quality of your colours!

Because the rays of the sun and

even the moon can penetrate the red

of the pigment cinnabar19.

or plants and which have been utilised in building or conserving and

protecting monuments. For example:

• it bleaches the colours of walls, changing the pigments in

frescoes and paintings;

• it turns varnishes used to protect paintings, wood and metals,

as well as other materials, yellow;

• it weakens organic18 adhesives (glues).

On monuments, the light of the sun and, specifically, the part

of the spectrum of sunlight, which is called ultraviolet radiation,

is responsible for most photochemical reactions in inorganic

materials and destroys all organic materials derived from animals18 οrganic materials: materials made of organic compounds derived from living organisms, e.g. resins,

fats, oils etc.19 cinnabar: Red vegetal pigment known since antiquity. Its chemical formula is HgS i.e. mercury (II) sulfide.

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The light of the moon destroyed

the colour of the walls in the peristyle of

the house of the secretary Faberius!

Some useful advice:

If you would like the red colour

of cinnabar to be preserved well

on your walls, you should polish

your wall with a brush dipped in

melted wax mixed with oil!

Light increases the temperature on

the surface of monument materials and can

cause a change in the relative humidity20,

different contraction and expansion in

between materials, fissures, breaks and

a decrease of their durability.

Are you sure, Vitruvius, that that piece

of information about moonlight has been

scientifically verified?

20 relative humidity: the ratio of the quantity of water vapours contained by air to the quantity that the air can “hold” at that particular temperature and air pressure (%)

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Biological erosion or bioerosion is the destruction of monument materials

with the passage of time by microorganisms, plants and animals living on,

near or in those monuments.

Colonies of millions of microorganisms...

... are discovered by environmental microbiologists in each gramme

of materials from monuments! Their presence and action there is

an absolutely natural phenomenon, as they are the agents by which,

slowly slowly, rocks, metals, wood are converted into soil and earth.

However, these microorganisms, however necessary they might be in

the geological cycle, are considered undesirable by man, when found on

the materials of monuments, which they destroy.

6. Biological erosion of the materials of sculptures and

architectural monuments.

Insects and spiders take refuge in recesses and

gaps between stonesof the monuments.

Many species of plants grow amongst the rocks of the monuments at Nafplio and destroy them with their roots, absorbing moisture and

giving food and shelter to animals and microorganisms.

The prefix “bio” means life in Greek.

Therefore anything “biological”

refers to the presence and

action of living organisms.

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Bacteria, fungi, algae and lichens develop on and in the materials

of monuments and destroy them by producing acids and other aggressive

chemical substances that dissolve and stain the materials irreparably.

Additionally, inside the pores of stone materials, their mass absorbs

the damp, expands, presses them and makes them break!

The presence of water encourages plant and microorganism growth on the material of monuments, such as the Koumoulou fountains on the island of Andros.

Black microbiological presence and growthon areas of monuments that contain more moisture.

Multi-coloured lichen growing on the northern façades of the Erechtheion on the Acropolis, perhaps because these expanses contain more moisture and

receive less solar radiation.

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Multicoloured lichen and snails grow on the northern sides of the rock of the Pano Kastro castle on the island of Andros, perhaps because

these surfaces contain more moisture and receive lesssolar radiation.

The black microbiological presence that develops in the fissures of stones in monuments destroys the stone with its chemical secretions,

while its mass absorbs humidity from the environment, expands and breaks the stone.

From a very early date, people observed

that the microorganisms that destroy

houses and belongings are favoured

by warmth and damp.

It’s true!

And if you don’t want your books destroyed,

make sure that your bookcases are

correctly oriented! Because in

rooms facing south or west,

books are destroyed by

worms and damp and

papyrus rolls moulder with

rot from the diffusion of

the damp air.

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Green moss grows on a portion of painted wall where water comes through, under the roof of an old house on the island of Icaria.

Many kinds of lichen disappeared from city monuments

due to atmospheric pollution. Lichens are very good

bio-indices of air quality and their presence is linked to

low levels of atmospheric pollution. Schedule a visit to

an archaeological site or monument guided by lichens21:

Try to identify the northern façade of the monument and

look for coloured lichen. If you don’t find any, you should

be worried about air quality in the region.

An activity to do at an archaeological site or monument:

Many different kinds of bryophytes and plants...

... grow on and next to sculptures and architectural monuments.

Moss grows on stone and wood parts of monuments on protected surfaces

with a low temperature and with humidity, destroying their appearance

and function.

21 lichens: complex organisms, composed of fungi and photosynthetic algae or cyanobacteria that live symbiotically. They grow on rocks, wood and stone monuments in the most extreme environments, but, as organisms are extremely sensitive to atmospheric pollution.

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The archaeological service regularly removes the many species of plants that grow amongst the rocks of Hadrian’s Arch in Athens and which destroy the rocks with their roots, preserving moisture and providing food and refuge to animals and microorganisms.

Regular and careful plant removal throughout the archaeological site of the Acropolis, done by hand and using a special weed-cutting machine is undertaken by trained personnel.

Conservators worry...

Weeds, low bushes and even entire trees can grow in fissures, in seams

between stones, in gaps and recesses of monuments. In other words,

wherever damp, dust and soil linger, i.e. the elements that help them

grow.

Plant roots destroy the monuments fragmenting them and turning

the stone into dirt. Furthermore, they maintain damp longer within the

stones and provide food and refuge to animals and microorganisms.

... because plant removal must be done often and with care, in order

not to harm the monuments. Additionally, chemical weed-killers

are usually toxic and dangerous for the environment, conservators

who have to apply them, but also to the materials from which the

monuments are made.

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The endemic plant Micromeria acropolitana was discovered yet again on the Sacred Rock of the Acropolis almost a hundred years after its “extinction”. Source: Tan, K., Tsounis, G., Tsounis, L. 2010 “Micromeria acropolitana (Lamiaceae) rediscovered in Athens (Greece)”,

Phytologia Balcanica 16 (2): 237-242.

The temple of Apollo in ancient Corinth by J.D. Le Roy circa 1755 from his work: “Les ruines des plus beaux monuments de la Grece” (1758).

© Universitätsbibliothek Heidelberg

... because the natural environments of monuments and archaeological

sites are often undisturbed by man and play host to interesting species

of plants and rare species of animals and birds or even species of trees

that bioaccumulate heavy metals22 from the atmosphere, protecting both

people and ancient monuments.

The romantic souls of European travellers in the 18th and 19th century

was similar, when they “discovered” painted and described the monuments

of the past as exotic ruins draped in greenery!

In his book “Pictures from Italy”, in 1846, Charles Dickens described the

landscape near the grave of Juliet in Verona as follows: “…fresh plants and

young flowers were prettily growing among fragments of old wall…”

Botanists and environmentalists are happy...

22 Heavy metals: metals with a specific weight greater than that of iron, which are toxic at low concentrations.

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http://www.verticalgardenpatrickblanc.com/realisations/paris/quai-branly-museum

Even today, the link between buildings and plants excites the imagination

of many different artists, including Patrick Blanc with his “Vertical Gardens”.

This modern French botanist is inspired by the flora of the world and

develops verdant gardens on the walls of public buildings. The result is

certainly spectacular. See the result of his work on the walls and the terrace

of the Museum at the Quai Branly in Paris:

... seek refuge in the recesses of monuments. Both in the cities and in the

countryside, birds are disliked by monument conservators, because their

metabolic byproducts23, besides being unsightly, are acidic and dissolve24

both stone and

metal in the same

way they destroy the

metal railings of our

balconies.

The museum conservators must have surely discussed

with the artist the negative effects that the plants’

root systems and the damp would have on the

building walls...

Various animals...

23 metabolic byproducts: non-useful products, which an organism excretes. In this instance, it means bird droppings. 24 To dissolve: a chemical process by which a chemical substance, whether solid, liquid or gas, is fully broken down into molecules or ions in another substance.

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Additionally, if metablic byproducts aren’t immediately removed,

they become sources of microorganisms, which further destroy the stones.

In the countryside, besides birds, abandoned monuments are also under threat from various

wild animals, which nest in the abandoned structures, as well as from sheep and goats

that scramble freely and graze off the greenery around and on them.

Acidic metabolic bird excrement dissolves the stone material of monuments.

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... whether caused by natural causes, forest fires and earthquakes, or by man,

due to negligence, arson or war, has in many instances threatened and destroyed

monuments, archaeological sites, settlements and even entire towns.

7. The destructive effect of fire on the materials of sculptures and architectural monuments.

A great fire that passes over sculptures and architectural monuments:

• burns and entirely destroys any parts made of wood, textile,

leather or paper

• melts or distorts any metal parts

• breaks and blackens stone and glass materials.

Firestorms...

Fire shows no mercy!

Stones as hard and porous as travertine,

which we Romans used on demanding projects,

including the Colosseum, can’t stand up to it and

are torn apart immediately, because their natural

composition includes a certain humidity,

part earthly element and a lot of air element…

When the fire draws these from the air,

it penetrates into their depths and settles into

the gaps of the fissures, creating a great fire and

thus sthe rocks start to burn.Aerial photograph of Thessaloniki after the great fire of 18-19 August 1917 (Source: «Incendie de Salonique. 18-19 Aout 1917», La service Aéronautique militaire de l’ Armee de Terre Francaise).

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What Vitruvius seeks to explain with

the knowledge of his time is that the greatest

damage caused by fire on the stone building

materials of monuments is the great and

sudden increase of cold surfaces beyond

the limits of elasticity25 and the forces

of cohesion26 of the crystals.

Crystals expand too suddenly, so the stones

are shattered and the structural material

is lost.

The very high temperatures that developed in the interior of the Erechtheion during the fire caused by a raid by Sulla’s Romans in 86 BC and also during the national War

of Independence in 1827, caused a rapid expansion of crystals and the typical scaling of the structural stones.

Finally, fire leaves behind pitted and “decarbonised” CaO stone

surfaces, with little cohesion between particles, which are very prone

to damage by water, air pollutants, plants and microorganisms.

25 crystal elasticity: the quality crystals have of being able to return to their initial shape after external pressure, that does not exceed the limit of their elasticity, has been exerted on them. 26 forces of cohesion: the attractive forces that keep the molecules of a chemical substance connected to each other.

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In architectural monuments, earthquakes are responsible

for movement of the structural stones, turning between

the column drums and distortion of capitals and walls.

Additionally they caused opening of joints, fissures and

rifts, broke stones and made segments fall.

At times we lose the earth from under our feet! The ground, the most stable

point of reference in our lives, moves! Architectural and sculptural monu-

ments are damaged. How does that happen?

8. The destructive effect of earthquakes and settling on sculptures and architectural monuments

When there’s an earthquake…

Earthquakes, their causes and consequences have always engaged the mind

of people, as from antiquity to this day they have caused fear and death,

and the destruction of many constructions. The Ancient Greeks considered

earthquakes were “Diosemia”, in other words a signal from Zeus, which at

a critical moment revealed the turn of significant events.

They considered that the Giant Enceladus was responsible for earthquakes,

whom the goddess Athena had been interred in Sicily; or even by Poseidon,

when he smote the earth with his trident.

Today we know that an earthquake is a shaking of the ground that we

feel when tectonic plates27 of the lithosphere28 move and exert pressures

between each other.

An earthquake was the reason for the movement between drums and the collapse of Phidias’ workshop and the palaeo-Christian church of Elis in Olympia, as well as the Heraeum at Samos.

Some seismic activity was the cause of the damage to the drums of the ancient monument behind the young King Otto, in this portrait by Gottlieb Bodmer (1804–1837). 27 tectonic plates: massive plates of the lithosphere, whose movement causes earthquakes.

28 lithosphere: the outermost mantle of the earth, which is made up of many lithospheric (tectonic plates).

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Before earthquakes, the god would always

send messages: constant storms or extensive

drought, great heat in the winter, darkening

of the sun in the summer (an eclipse of the sun),

the wells would run dry, there would be

strong winds, great flames would cross the sky

(comets, meteor falls)…

It is likely that subsidance due to an earthquake

is how Lake Kaiafa came into existence in

the south-western

Peloponnese, near

the bay of Cyparissia,

as when I visited

the area, in the

2nd century AD

there was no

lake there.

Today, even though this phenomenon

has been explained through the tectonic plate

movement model, seismologists agree that

it is very difficult for anyone to predict when

and where an earthquake will take place and

what its magnitude will be.

In their attempt to protect themselves, people have always tried to pre-

dict the appearance of an earthquake.

Subsidence is the sinking or collapse of the ground that happens due

to compression caused by a human construction.

When does an earthquake happen?

Τhe phenomenon of subsidence certainly is also

related to factors such as morphology29 and soil

quality, rainfall and seismic activity in the region

as well as other factors.

29 terrain morphology: the study and description of the exterior features of the ground as these have become since they took shape and with the passage of time.

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In monuments, subsidence results in the separation of the weight-bear-

ing function of the different parts. The walls of the entire monument or

parts thereof are shifted and lean until a new static balance is achieved.

In general or total subsidence events the monument is swept along uni-

formly and usually there are a few small cracks. In differential subsidence

events, the ground and the monument shifts unevenly, pressure is exerted

and many different and large cracks form in various directions and angles.

Ground subsidence is responsible for the angle of the Leaning Tower of Pisa.

The Leaning Tower of Pisa in Italy is the best-known

example of a monument that leans, as it has shifted

due to ground subsidence!

But even in Greece, the ground below the

archaeological site of Olympia settles by

1-2 millimetres a year.

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Ground subsidence in Olympia has scientists worried about the stability

of the ancient monuments. Source: St. Krikki “Olympic… subsidence”,Ta Nea Newspaper, 21/12/2009

Ancient Olympia is “sinking”The archaeological site of Ancient Olympia is “sinking” at a rate of up to 1.6mm per year, as Greek scientists discovered with the help of satellites. The sinking may have commenced hundred of years ago and is due to the land on which these ancient buildings were built.

Experts have research 15

square kilometres of Ancient Olympia

in order to ascertain which points and

sinking faster.

Annual sinking in millimetres

Prytaneio

The Temple of Zeus

Leonideion

The workshop of the School

of Archaeology

The village of Ancient Olympia

A satellite monitors the settling.

The soil PlioceneThe rocks on which the foundations of Ancient Olympia were laid date from the Pleiocene. They started to be formed some 5 million years ago and the process was completed some 1.8 million years ago.

The soil is made up of conglomerate rocks, which are products of mechanical fragmentation, moving fluid matter, clay and non-cohesive mud.

Satellite at an 800 km orbit

It emits a ray of microwave radiation on the monument every 35 days. The time of reflection of the ray is recorded so it can be compared to the next one.

35 days later, if the ray needs more time to be reflected, it means that the distance has grown due to sinking of the ground.

East of the city of Olympia

The Academy of Olympia (the Cronian Hill)

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Ever-increasing human activity has resulted in the emission of immense

quantities of pollutants30 into the environment destroying the quality of

the air, sea and soil and all the groundwater on the planet. The consequences

are dire for the health of all living organisms and monuments too.

9. The destructive effect of environmental pollution on the materials of sculptures and architectural monuments

Air pollution…

In the twentieth century ever-increasing use of fossil fuels (petrol, lignite,

natural gas) for transport, heating and energy production by humans has

helped resolve many everyday problems.

At the same time, however, it has liberated and continues toliberate immense

quantities of pollutants into the atmosphere, that have irreparably changed

our air quality and accellerated greatly the destruction of architectural mon-

uments. Various pollutants, and specificially sulphur and nitrogen oxides,

along with the humidity in the atmosphere:

• they convert the stone surfaces of monuments into soluble gypsum

(sulphation / gypsumisation)31 and erode the metal parts of monuments

far faster. Outdoor bronze monuments rapidly gain their characteristic

verdigris green surface layer.

• increase the acidity32 and dissolving action of rain. “Acid rain” as it

is called, is a rain that falls on the stone monuments of cities and polluted

industrial areas and dissolves and washes off the surface layer of sulphated

marble. Along with the gypsum layer various details of the sculpted decoration

or the processing of the marble are lost too - ancient and historical inscriptions,

traces of colour and much more. In their place we sea marble that’s been “eaten

away”, rounded-out and “bleached in spots”. Even on metal monuments, acid

rain dissolves and washes away the surface products of corrosion far faster,

removing sculpted details and staining the entire monument with “rivulets”.

Loss of sulphated marble relief from the sculpted decoration of the monument of Hadrian’s Arch in Athens.

30 pollutant: a chemical substance that harms the environment. 31 sulphation / gypsumization: the destructive process by which marble is converted into easily soluble gypsum, as it reacts to sulphur oxides and atmospheric humidity. 32 acidity: a measurable property of solutions, which expresses how acid a solution is. When the pH of

a solution is low, its acidity is high.

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At the same time, the burning of fossil fuels also frees into the atmosphere

many very small particles (particulate matter or particle pollution) that remain

suspended for a great length of time.

These can be soot, smoke, dust, asbestos fibres, pesticides, petroleum

hydrocarbons and/or certain heavy and toxic metals. Particulate matter33 is very

dangerous for our health.

In the case of monuments::

• they settle on the adsorptive layer of gypsum on the surfaces that are

protected from the rain and form blackened crusts / encrustations, while

• they retain damp and rust metal materials far more rapidly.

Formation of a blackened crust on surfaces of the monument of Hadrian’s Arch in Athens that are protected from the rain.

The use of private cars next to monuments in cities - as is the case with Hadrian’s Arch in Athens and Hagia Sophia in Istanbul - is injurious to air quality and to the surfaces

of monuments due to increased levels of particulate matter.

33 particulate matter: the solids or liquids dispersed suspended in air, which have a diameter of 0.0002-500 μm, including dust, smoke and fly ash. Large and dark-coloured particles are perceived as smoke, while those that are smaller are only visible using a microscope. Their nature and chemical composition depends upon the place, the season and the weather.

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The ground and groundwater are polluted...

... by human industrial and agricultural activities with heavy metals, fertilisers, organic compounds and salts, poisoning plants, animals and humans.

Polluted groundwater rise up the materials of the area’s monuments, transporting within the structural components dangerous salts, which crystallise34,

exert pressure and break the stone material and also nutritional elements that act as fertiliser and favour the growth of destructive plants and

microorganisms.

Air pollution in combination with extensive damp is due to the vivid green erosion of the bronze monument of Saint George in Berlin, Germany.

35 crystal: a solid material whose atoms or molecules are arranged in a specific three-dimensional pattern.

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The term “climate change” refers to the alteration of meteorological

conditions that extend over several years. To date, climate changes were due

to natural processes. Over the last few decades, however, most specialists

can measure and record with precision significant changes in temperature,

wind and rain in all parts of the planet and believe that the earth’s climate

is changing due to human activity. According to their estimation, Greece is

expected to face a rise in sunshine, average temperature and northern winds

and a fall in rainfall. As can be expected, climate change will affect all

living organisms, the environment as well as the monuments found within

that environment.

According to these scenarios, a rise in temperature is expected to speed up

all chemical reactions, including stone sulphation and salt crystallisation.

It is also expected to favour the plants and microorganisms that are

heat-resistant.

An increase in solar ultraviolet radiation35 will favour microorganisms

that produce more dye, staining the monuments in unforeseen ways.

At the same time conservators fear that various orgnaic materials that

have been utilised during their construction or conservation e.g. colours,

glues, varnishes, will be destroyed far more rapidly.

8. The destructive effect of climate change on sculptures and architectural monuments

Coastal monuments, like the Castle of Methoni, will be at risk from rising sea levels due to the forecast rise in temperature.35 ultraviolet radiation: from the rising level of the sea due to the expected rise in temperature.

Part of the spectrum of electromagnetic radiation with a wavelength of 380 to 60 nanometres.

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Increasing north winds are expected to intensify wind erosion and slow

down the rate of deposition of airborne/gaseous pollutants and particulate

matter. Finally, a rise in the sea level will pose a direct risk to all those

monuments located within 3.360 km of the Greek coastline and indirectly

to the more continental monuments, enriching the groundwater with salts.

An action of the environmental group Greenpease to raise public consciousness on the matter of climate change and its adverse effects on monuents around the world.

We also expect something good:

With climate change incertain locations,

there will be less damage from frost and

from the rate of deposition of acid pollutants.

Whatever the case, we’re hearing

about these for the first time...

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However, climate change is nothing new.

You should remember that on our planet,

a rise in temperature due to natural causes

also took place during the Holocene

(12,000 years ago). This appears to have

coincided with the age of floods and appears

to have been recorded in the mythology

of the entire ancient world. You remember

Deucalion and Pyrrha…

Deucalion said that

he is since buried in

the precincts of the temple

of Olympian Zeus in Athens…

Now that’s a monument!

The main causes of climate change are an intensification of

the greenhouse effect and the hole in the ozone layer.

The greenhouse effect...

... is a natural process according to which different atmospheric gases,

such as carbon dioxide, water vapours and methane that are concentrated in

the higher levels of the atmosphere. This is where most of the solar energy

that the earth receives is absorbed, so that it isn’t reflected back into space.

Thanks to this phenomenon, the temperature rises, spring comes to the earth,

the plants blossoms and bear fruit and animals and humans grow.

The greenhouse effect.

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The hole in the ozone layer

The ozone layer is located at the highest point of the Earth’s atmosphere and

protects all the various life forms on the planet from the sun, absorbing a significant

part of the ultraviolet radiation. The massive emissions of fluorochlorocarbons

into the atmosphere resulted in the creation of a great hole in the ozone layer

above Antarctica, which has already had negative effects on the health of all

living organisms, while it also contributes to the rise of the planet’s temperature.

The problem began with the ever-increasing burning of fossil fuels and the

production of fluorochlorocarbons. Because of these massive quantities of

greenhouse gases are emitted, trapping more heat and gradually affecting

the climate, nature and monuments worldwide!

The largest hole in the ozone, which was recorded over the Anterctic.

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Desertification is the gradual loss of soil fertility due to a variety of natural

factors, but also due to human activity. This phenomenon constitutes

a serious problem for countries of the Mediterranean and for Greece,

because, besides the fall in soil productivity, it is directly linked with the

destruction of natural landscapes and the monuments they frequently hold.

In Greece 35% of the country’s territory is deserted or faces a high risk

of desertification, while a mid-level risk of desertification is faced by 49%

of the country’s land mass.

11. The destructive effect of desertification of the land on sculptures and architectural monuments.

KEY Low riskMedium risk due to erosionHigh risk due to erosionHigh risk due to (illegible)Lakes Cities

Potential risk of desertification in Greece.

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There is an immediate threat for land in the Peloponnese, Western Sterea

Hellas, Crete, Euboeia, Epirus, Thessaly and Thrace, and thus to the

monuments they hold.

In our days, however, it is also strongly linked with human activity,

as this develops faster in some places faced with exhaustion of

underground water supplies, overgrazing, wrong agricultural practices,

illegal plant cutting and lumbering, forest firers and others.

Overgrazing is one of the main causes of desertification of the ground.

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Those who are responsible for the good maintenance of monuments are

frequently called upon to decide about whether to limit or block visitor

access to that monument. This is because crowds of visitors to cultural

heritage sites and their often thoughtless behaviour frequently causes

irreparable damage to monuments and a headache for conservators.

12. The destructive effect of visitor behaviour on monuments The most usual “problems” caused by the public is the use of flash photography;

touching exhibits or fragile surfaces on a monument; crossing safety barriers

that are required for an exhibit and going into roped-off areas that are there

to ensure the safety of the exhibit or the monument, but also that of the visitors.

A large number of visitors at theh Guell park of Parcelona admires Antoni Gaudi’s architectural work of Antoni Gaudi.

The large number of visitors at the Acropolis monuments during the summer months makes it very difficult to control their behaviour.

A large number of enthousiastic tourists climb between Karl Marx

and Friedrich Engels to be photographed.

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In any case, all monuments hold a particular symbolism in our conscience,

both that of the conqueror or representative of an unwelcome regime,

and that of the opponent, who is in defence or offers resistance. Typical

examples are Morosini’s Venetian force bombarding the rock of the

Acropolis when it was held by the Ottomans in May 1687; another

is the burning of the Bastille by the revolting people of Paris in 1789.

Vandalism is any partial or total destruction of a monument by a human,

done with intent. The term came from the germanic trive of the Vandals,

who used to destroy statues and works of art, which they encountered in

their military campaigns.

At a time of military clashes or civil conflict, people destroy monuments

even more by bombing, theft, fires etc. Sculptures and architectural

monuments are often targeted by invadors because their pride fo place or

strategic positioning in an inhabited area.

13. The destructive effect of vandalism on monuments

Traces of bullets in the weight-bearing

stones of the Acropolis Parthenon in Athens.

The recent arson at the Etz Hayyim Synagogue in Chania caused the loss of valuable old books.

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At time of peace, there are no few numbers of monuments that

are vandalised. Many monuments were dismantled36 and taken down37

in a more or less destructive manner at times of regime change;

while even during smooth democratic processes, individuals or groups

in ignorence and less interested in the value of monuments continue to

destroy them, stealing any precious parts or altering them with painted

sprays and scratches.

Morosini shelling the Acropolis in 1687. Engraving. Source: Francesco Fanelli. Atene Attica: Descritta de suoi Pr̀ ιncipi. Fino all’ Acquisto Fatto dell’ Armi Veneti nel 1687, Venice, 1707.

36 dismantled: The loss of the original power of prestige and values that once had an object. 37 taken down: The disconnection of the pieces that make up an architectural building and their removal.

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The illicit trade in antiquities refers to the stealing one country or

community’s cultural heritage being stolen by another. Greece as a country

has undergone many painful consequences of this illicit trade in antiquities

due to its long and extensive cultural heritage.

It is well known that during the Ottoman rule and the war of Greek

independence, various ancient Greek monuments were destroyed after

their sculpted decoration was removed in part or in its entirety by European

admirers of Ancient Greek art.

The best known exaple of this are the Parthenon marbles, stolen by Lord

Elgin in 1801-1812, and sold to the British Museum, which our country

has asked insistently to be returned. But there are also portions of the

sculptures of the temple of Aphaia on Aigina, which now decorate the

Munich Glyptothek; the icon of the Removal from the Cross from the

Sacred Monastery of Timios Prodromos in Serres and so forth.

However, works of human creation, expression and religious worship aren’t

the only things that people are demanding be returned to their homes. In

our days many communities of natives / aborigines from America, Canada

and Australia are demanding that the great museums of the Western

world return relics stolen by European travellers and naturalists during the

centuries of colonial rule in the name of anthropological studies. In our

parts the request for the return of holy relics of saints are better known.

The illicit trade in antiquities always found a fertile field in countries that

are at war; or were politically or financially unstable, like Syria now, up

to recently Iraq and, in the 19th century, Greece.

14. The destruction of monuments due to the illicit trade in antiquities

The “Aigenites”, sculptures from the pediments of the temple of Aphaia on the island of Aigina were taken out of Greece by German and British illicit excavators shortly before the Greek War

of Independence broke out. Today they are exhibited at the Glyptothek in Munich. Source: The Vema Newspaer 20/3/2011.

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Athens, 2015

Project coordinatorMaria Lagogianni, Ph.D. (Archaeology)Souzana Choulia – Kapeloni, Archaeologist

General editingTonia Koutsouraki, ΑrchaeologistAlexandra Seleli, Αrchaeologist - Μuseologist

Graphic Design editorSpilios Pistas, Graphic artist

TextsSofia Papida, Conservator of Antiquities and Works of Art - Museologistς

Translation into EnglishKaterina Apostolaki, Translator - Interpreter

Digital and graphic designPashalia Tsagarian, Graphic designerIrene Charalampidi, Graphic designer

IllustratorElias Karras, Painter

© 2015 Ministry of Culture and SportISBN 978-960-386-216-1

The leaflet “Learn more…. about the causes of causes of destruction of sculptures and architectural monuments” under the theme “Preventive conservation: a shield for protecting monuments” was created and digitised in 2015, within the framework of Action code no. MIS 339815 “Updating and digitizing educational material to support the educational process, which is implemented by the Directorate of Museums as part of the Operational Programme “Education and Lifelong Learning” and jointly funded by the European Union (European Social Fund) and by national funds.

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