The western edge of the Belvedere hosts the Grotta di San Bonaventura, an ancient Etruscan tomb dug into the tufaceous rock. According to legend, when he was a child, Giovanni Fidanza (future St. Bonaventure) was healed from a serious illness thanks to the intercession of St. Francis. His mother, Maria di Ritello, brought his son to the cave and laid him down on the same pallet where the Assisi saint used to pray during his visit to Bagnoregio. Today, the Grotta lures visitors and pilgrims. The geologists of the Museo Geologico e delle Frane have been supervising the cave and monitoring the cracks sited on the vault.
