It is one of the most remarkable monastic churches in Italy, where the peaceful and serene atmosphere has been the result of the realization of a simple, unadorned late Romanesque interior.
It was completed in 1265. The inside has a nave and two aisles with pointed arches supported by cylindrical pillars.
The gabled façades has a magnificent rose window. The paintings decorating this church are of great value; there are many medieval frescoes, a XVIth century altar-piece by Romanino and a remarkable cloister of the end of the XIVth century.