The friary’s Museum of the Osservanza, housed in the room next to the sacristy, is dedicated to Father Aurelio Castelli, head of the convent from 1867 to 1894. A great scholar, he helped to restore the independence lost with the 1866 suppression, which caused the loss of a substantial part of the artistic and literary heritage of the Observance.
The museum began to take shape in 1910 when this room was chosen to house the fresco depicting the Last Judgment by Giovanni di Benvenuto, originally placed on the wall at the bottom of the crypt. A collection of pieces of furniture and works of art from the Basilica gradually built up, and ten years later the Museum was officially inaugurated.