The Archiepiscopal Museum is housed on the first floor of the Archiepiscopal Palace and contains many works of art from the old cathedral and other buildings that no longer exist. It also holds the famous throne of Maximian - a work of a 6th Century Byzantine artist, one of the greatest ivory masterpieces of all times. The Palace also houses the Oratory of S. Andrea (or archiepiscopal chapel) built in a Greek cross plan with vaults decorated by early 6th Century mosaics. The museum is a major deposit of the Curia for ancient works.