Built from the 1C AD, it has, like the Greek theatre, taken advantage of the configuration of the terrain, at least for one of the hemicycles, which is hewn directly out of the rock. The function of the rectangular cavity that in the centre of the arena and is linked to the entrance by a moat was to store material. The water used for nauchmachiae and to clean the arena after the combatants' bloody exit was kept in a basin on the right of the pre-Norman chapel, San Nicolò dei Cordari.