St. Mary Cathedral, built on the area of the ancient St. Basilio Church, was finished in 1474, when the highest part of its façade was completed by L. Riccomanni, on the top of which, later (1735) were added the statues of St.Eutichiano, on the left, Sergio VI, on the right, and Niccolò V in the middle.

The façade, covered with white marble, is opened by a gothic portale on which there is a still gothic rose window, and it is bordered by two lateral structures of the XVII century.

The one on the right is the embattled church tower, opened progressively by windows with one light and windows with four lights, the only remains of the ancient St. Basilio Church.

It is a church with nave and two aisles and a wooden ceiling carved by P. Giambelli between 1662 and 1670.

There are paintings of Solimena, Fiasella (The Visitation of Mary to St. Elisabeth) and others, sculptures of L. and F. Riccomanni, a Della Robbia school terracotta.

A particular mention deserves the so called Chapel of the Crucifixion, on the left of the altar, where it is kept a canvas representing Christ, a picture that Mastro Guglielmo made in 1138, a fundamental work for the Romanesque painting.