Next to the cathedral is a medieval building, that was once the ancient bishop’s see. On the ground floor is the original sacristy of the treasure of Saint James, now kept in a section of the Museum of the Antico Palazzo dei Vescovi, is located in the same palace. The archaeological collection is found on the lower level, with displays of finds and artefacts from the archaeological excavation carried out there.

The building is part of the Fondazione Pistoia Musei’s new museum system, along with San Salvatore, an exhibition venue that uses visual, sound, and tactile language to tell the story of the city’s ancient centre, Palazzo de’ Rossi, a centre dedicated to art of the 20th century in Pistoia, and Palazzo Buontalenti, home to temporary exhibitions.