The Roman amphitheatre was built in the second half of the first century. B.C. outside the Cassino’s city walls, exploiting and shaping part of the natural slope.
The building was used for fights of wild animals and shows of gladiators and has a rather small elliptical plan.
Inscriptions found report that the generous matron, Ummidia Quadratilla, built (or perhaps simply restored) at her own expense the amphitheater and a temple, of which no trace remains.
The stands could hold around 4500 spectators who came through three large openings, while the two major gates in the axis of the theatre allowed entry to the arena without going underground. A higher entrance provided access to the gallery for the authorities (tribunal).
The amphitheatre was the subject of constant plundering throughout the Middle Ages.