The Chiostro del Capitolo can be reached via a long vestibule from the church of S. Elena. Also known as the Chiostro del Duomo, this Roman-style building was built circa 1140. It stands on the former site of a Paleo-Christian basilica, and part of these remains is still visible today. Inside, the colonnaded arches with their large red marble columns are incredibly beautiful and the remarkable mosaic floors add to the effect. In the centre is a parapet over a 15th Century well. In a corner of the cloister stands the Carcer caplitis (prison of priests).