Only a few traces of this imposing theatre built in the first century AD can now be seen, incorporated into later buildings following the original outline of the tiers of seating.

Close to the forum, the theatre, probably built by order of Caesar Augustus, was part of the plan for the urban development of Rimini promised by the emperor.

Semicircular in shape, the theatre had an external diameter of about 80 metres, and the stage was some 23 metres wide.

The seating tiers, completely self-supporting, were carried on radial and concentric walls, made in concrete faced with brick. Corridors covered by barrel-vaulted ceilings gave access to the steps leading to the seating area.

Only a section of a column more than four metres in height and a few marble decorations remain of the refined and grandiose structures of the stage.

Concealed for centuries but never completely cancelled from memory, as shown by several mediaeval sources, the theatre was "rediscovered" in the early 1960's thanks to the intuition of Mario Zuffa, then director of Rimini's library and museum. Zuffa was also responsible for the finding of a fragment of a stone inscription near the church of San Michelino in Foro, with a text referring to the decoration of the theatre in the early years of the Roman Empire.