Le Balze is a deep, eroded limestone ravine about 2km northwest of the city centre that has claimed several churches since the Middle Ages as the buildings tumbled into its deep gullies. A 14th-century monastery, perched near the precipice, seems perilously close to continuing the tradition. To get there, head out through Porta San Francesco, the city's northwestern gate, along Via San Lino and follow its continuation, Borgo Santo Stefano, then Borgo San Giusto.