Near the Massa Martana train station, in a place remained unchanged and easily accessible on foot, is a completely intact Roman bridge built with perfectly squared massive blocks of travertine in a single arch. It granted passage on the ancient Via Flaminia over the Fonnaia river. The Fonnaia bridge hasn't changed since the restoration of the Augustan period (27 AD), is 15 m long, 8 m high, with a single circular arch of 3.5, has a lower slanting surface so that the road above can maintain its geometric axis. On the inner surface of the arch the blocks are disposed in even rows, and marked by letters and numbers that indicate the quarry.