Built in the 12 C and altered in the15 C, it has an amazing mosaic pavement created between 1163 and 1165 by a priest, Pantaleone: the decoration in almost primitive shapes is fascinating both for the freshness of the colours as well as for the liveliness of the poses and the richness of the symbols. Also noteworthy is the huge crypt divided into five spaces and resting on a forest of old capitals.