The Roman Theater of Teanum Sidicinum was built at the end of the 2nd century BC. The Theater was part of an architectural complex consisting of a large artificial terrace on which there was also a temple which seems to have been dedicated to Apollo. When, at the beginning of the third century AD, the theater was completely renovated at the behest of the imperial, at the instigation of Septimius Severus and completed by Gordian III, it assumed grandiose forms. In late ancient and medieval times on the ruins of the building, which probably collapsed due to an earthquake, a construction site was set up for the recovery and reuse of architectural marble materials. Between the 12th and 13th centuries an artisan district was built on the now underground cavea for the production of bricks and ceramics. In the modern age of the ancient theater only a vague memory remained. A country lane passed over the ruins of the scene, mounted on the now almost buried structures and slipped under the vaults of the median ambulatory to then exit and continue towards the medieval center. The ancient and hidden aspect of the ruins led to the area being called "the Caves" and, to protect the traveler, a chapel with an altar dedicated to the Madonna was installed. The first systematic explorations of the monument were carried out in the early 1960s by Werner Johannowsky. After some excavation and restoration interventions in the second half of the 80s, starting from 1998 an articulated project of exploration, restoration and enhancement of the site was conceived, which lasted over a decade. The discoveries that took place over the years made it possible to clarify many aspects of the monumental complex and the restorations carried out, both with national funding and with European Union funds, made it possible to return the ancient building to public use, which could also host important theatrical performances. An entire sector of the Archaeological Museum of Teanum Sidicinum is dedicated to the Theater of Teano, with reconstructive models of the complex in its various phases, architectural remains, including richly decorated architraves and capitals, and sculptural apparatus of great value.