The theatre was built in the late 1st century BC. Before its construction, two walls were built alongside the Adige River, between the Ponte di Pietra and the Ponte Postumio, to protect it against floods.
Today only remains of the edifice are visible, recovered starting from around 1830. They include the cavea and the steps, several arcades of the loggias and remains of the stage.
Part of the cavea was occupied by the church of S. Siro, built in the 10th century and restored in the 14th century.
At the top of the hill there was an ancient temple, built on a series of terraces.