It is an exteriorly rusticated Romanesque church, striking for its circular shape. The main structure was built in the 11th century on the ruins of an earlier basilica (S Maria Maggiore). Near the entrance is the pink Veronese marble sarcophagus of Berardo Maggi, while in the presbytery is the entrance to the crypt of San Filastrio. The structure houses paintings by Alessandro Bonvicino (known as il Moretto); two canvasses by Girolamo Romanino, and paintings by Palma il Giovane, Francesco Maffei, Bonvicino, and others.