It’s always much less busy than other sites in the city—and we have no idea why. An “old hospital” might not sound too enticing, but this huge building has treasures hidden away in its eerie corridors. One of Europe’s first hospitals, probably founded around 1090, raised abandoned children, took care of the infirm, fed the poor, and lodged pilgrims who stopped in Siena as they made their way to and from Rome. These activities are recorded in scenes in the Sala del Pellegrinaio (Pilgrims’ Hall), where colorful depictions of patients and healers from the Middle Ages looked down upon rows of hospital beds as recently as the 1990s. Along with the “Allegory of Good and Bad Government and Their Effects on the Town and Countryside,” these are some of the finest secular works of the period. The color-rich 15th-century frescoes by Domenico di Bartolo and others show surgeons dressing a leg wound and holding a flask of urine to the light and caregivers offering fresh clothing to an indigent young man. One of Bartolo’s panels encapsulates an orphan’s lifetime experience at the hospital, as he pictures infants being weaned, youngsters being instructed by a stern-looking mistress, and a young couple being wed (young women raised in the hospital were given dowries). As these activities transpire, a dog and cat scuffle, foundlings climb up ladders toward the Virgin Mary, and wealthy benefactors stand on Oriental carpets.

Elsewhere in the hospital complex are other frescoes and altarpieces commissioned by the hospital as it acquired huge landholdings and considerable wealth over the centuries. One gallery houses some original panels from Jacopo della Quercia’s 14th-century fountain in the Piazza del Campo, the Fonte Gaia. In the cellars is the dark and eerie Oratorio di Santa Caterina della Notte, where St. Catherine allegedly passed her nights in prayer. The city’s National Archaeological Museum occupies the labyrinthine lower floor; in Bambimus, art is displayed at child’s-eye height.