The nave which leads to the central dome is in three bays, with piers supporting a barrel-vault, the highest of any church. The nave is framed by wide aisles which have a number of chapels off them. There are also chapels surrounding the dome. Moving around the basilica in a clockwise direction they are: TheBaptistery, the Chapel of thePresentation of the Virgin, the larger Choir Chapel, theClementineChapel with the altar ofSaint Gregory, theSacristyEntrance, the lefttranseptwith altars to the Crucifixion of Saint Peter,Saint JosephandSaint Thomas, the altar of theSacred Heart, the Chapel of the Madonna of Colonna, the altar of Saint Peter and the Paralytic, the apse with theChair of Saint Peter, the altar of Saint Peter raisingTabitha, the altar of theArchangel Michael, the altar of theNavicella