Fodor's Expert Review Collegiata di Sant'Orso
Originally there was a 6th-century chapel on this site, founded by the Archdeacon Orso, a local saint. Most of the structure was destroyed or hidden when an 11th-century church was erected over it. If you go up the stairs on the left from the main church you can see the frescoes of Christ and the apostles (ask the sacristan, who'll let you in). Take the outside doorway to see the church's crowning glory, its 12th-century cloister, enclosed by some 40 stone columns with carved capitals depicting scenes from the life of St. Orso.