Built in the imperial era, it has, like the Greek theatre, profited from the configuration of the terrain, at least for one of the hemicycles which is carved directly into the rock. In the centre of the arena, the rectangular cavity, linked to the entrance by a moat, was intended for storing equipment. The water used for water displays and for cleaning the arena of the blood of the combatants, was kept in a basin on the right of the pre-Romanesque chapel of San Nicolo dei Cordari.