Located in the sacristy of the choir of the church of Sant’Orso, it contains important 14th and 15th century objects made of precious metals, including the silver relic chest of Sant’Orso from 1359, the large 14th-century chalice of Sant’Orso, the silver relic statue of Sant’Orso, astylar crosses, staffs, chasubles and exquisitely embroidered vestments. 

The objects of greatest historical and artistic interest include the missal of George of Challant dating back to the beginning of the 16th century. 

The archives preserve important ecclesiastic documents (the oldest dating back to 1025), liturgical manuscripts and a cartulary from the 15th century.