The museum hosts the Treasure of the Cathedral, which had long remained under lock and key. Among the most interesting works on display, a 15th century triptych, known as the Triptych of Clement VII, allegedly by Flemish painter Rogier Van der Weyden. Rich 16th, 17th and 18th liturgical vestments can be seen, as well the much older ones which belonged to Saint Augustine. On the first of the three floors of the museum there is a small but precious collection of silver chalices, crosses and shrines, some of which date back as far as the 14th century. At the moment, information in the museum is only in Italian and so are the guided tours.