The city of Susa, of Celtic origins and known as Segusium after the Roman conquest was established in a strategic position at the convergence of two roads that lead to Montgenèvre (Via ad Galliam) and to Mt. Cenis. Walking in its old town, you’ll find a number of precious historical evidences: the Arch of August located up the Via degli Archi, celebrates the alliance between Cotius and Augustus; the crucible rock probably used in ancient Celtic rituals, the ruins of Gratianus aqueduct from IV AD, the castrum (buildings and plots of land reserved to or constructed for use as a military defensive position), the antique arena dating back to the II century AD, still used for events and shows. And more, the Porta Savoia (III-IV AD) and the adjacent St. Just Cathedral, the remains of the ancient walls along Via dei Fossali. Finally in Piazza Savoia traces of an ancient temple emerged during recent archaeological excavations.