In 1976, the museum was enlarged to accommodate works from the entire diocese including the prestigious reliefs from the pulpit of Donatello.

In 1980, the vaults under the cathedral's transept were added to the museum's space, and other areas were included between 1993-1996, beginning work, only recently concluded, to reconnect the various sections into one single itinerary that passes through a few rooms in the old Palazo dei Proposti, around the harmonious Romanesque cloister, and concluding under the cathedral.

A reorganization of the museum space began in 2007, and plans include the preparation of the Renaissance rooms.

[1] An established itinerary guides the visitor through six rooms containing numerous and varied works of art, passes through an archeological section and the Romaesque cloister, and finishes with the Antiquarium and the vaults.

The excavation allowed for the recovery of various archeological items, which attest to the habitation of the area from the Etruscans to the Lombards.