The Diocesan Historic Archive has an extension of 1000 m², divided into 5 different sections, independent but complementary: conference room, management office, laboratories, storages and study halls. It collects 450 scrolls from the XII to the XX.

There are kept state documents from the Middle Ages to the 20th century, documents of the magistrature of the ancient Kingdom of Sardinia and of the Italian State (1323 - XX century), ultra centennial notary deeds, etc.