The foundation of the Hospital, located right next to the Church, is also associated with the Confraternity. The building features a smooth gabled facade with a central oculus and a single nave. The interior was decorated between the 14th and 15th centuries with an initial cycle of frescoes. In the early 1500s, it underwent a restoration that profoundly changed its appearance and introduced a new internal painting decoration that is still visible today, depicting episodes from the life of Saint Catherine and scenes from the Passion of Christ.
The hospital continued to operate until the early 1900s when the new civil hospital was built.