180 m long, 2,40 m tall and 1,80 m wide: it is made of small irregular pink limestone blocks fastened with mortar and has a floor and walls made of cocciopesto (lime mortar with crushed bricks). They are waterproof (from water cleaning) and go up to the unfinished vault, which must have originally had a wooden covering and has square openings to allow the passage of air. This structure continues underground up to the amphitheatre, just like in the past.

It is a via tecta, a passage for gladiators, set designers and for dead beasts. Nearby the “barracks for gladiators” must have been built: today it is an embankment facing the XII century apse of the San Rufino cathedral of San Rufino, with a view of the southeastern part part of the city and the profile of St. Clare’s Basilica