This former hospital, parts of which date from the 13th century, was built as a hospice for pilgrims travelling the Via Francigena pilgrimage trail. Its highlight is the upstairs Pellegrinaio (Pilgrim's Hall), with vivid 15th-century frescoes by Lorenzo Vecchietta, Priamo della Quercia and Domenico di Bartolo lauding the good works of the hospital and its patrons.
The building is now a cultural centre and houses three museums. The pick is the atmospheric Archaeological Museum set in the basement tunnels. Also don't miss the medieval fienile (hayloft) on level three, which showcases Jacopo della Quercia's original sculptures from Siena's central Fonte Gaia fountain.
