The south gate of the medieval walls, the smallest and quietest of the three. It opens onto the slope that climbs out of the town toward the surrounding hills and the old hilltop villas — Pievecchia, Grignano, Monterifrassine.
The arch and the adjoining stretch of wall are easy to miss if you're not looking for them, tucked into the modern fabric of houses that have grown up against the old fortifications.