Principal church of the town, was the place where the Doges were ordained (it was dogal chapel up to 1807, the year when it was elected cathedral of Venice, place previously occupied by S. Pietro in Castle). It was built in the ninth century: in the 829 began the works for the construction for welcoming St. Mark's the Evangelist mortal remains, stealed the preceding year from Alexandria of Egypt, for hand of some Venetian merchants. So the church replaced the one consecrated to St. Teodoro, who was the first patron of Venice. It was object of renovations and new realizations, always on the original foundations but it always maintained the characteristic profile of the Byzantine church, with Greek cross plan and central dome edged with others four round form domes that end with bulbiform little domes. During the sixteenth century, the Sansovino consolidated its structure, in the seventeenth century there were some inner interventions for the completion of the altars of the Sacrament and of the Madonna Nicopeia; in the eighteenth century some mosaics were remade. Just gold bottom mosaics are the biggest wealth of the Basilica, both for their extension, they in fact spread on a surface of 4.240 square meters, and for the antiquity of their dating.