It was built in the late reign of Augustus, some decades after the foundation of the city (25 BC), as testified by the presence of pre-existing structures in the area.
The theatre occupies three blocks annexed to the ancient city walls, along the Roman main road (the decumanus maximus, next to the Porta Prætoria.
The cavea was enclosed in a rectangular-shaped wall including the remaining southern part.
This was reinforced by buttresses each 5.5 metres (18 ft) from the other, and included by four orders of arcades which lightened its structure.
The scene, of which only the foundations remain, was decorated by Corinthian columns and statues and was covered with marble slabs.