Amphitheater
Archaeological investigations have brought to light a good part of the amphitheater of Trebula Mutuesca. The building has an elliptical form (94 × 66 m), and was constructed in part in opus mixtum and in part built into the rocky bank. The arena was given a subterranean gallery for the use of the lifting machines which were employed during the spectacles. The cavea rests on vaulted areas, probably connected to the gaming activities of the amphitheater. In the area of the same structure there was also a complex system for the collection and distribution of water, with wells, cunicoli, and drainage pipes. Remains of inscriptions attest to renovations in the Trajanic period.

Area of the so-called Temple
Research started at the end of the 1950s close to the amphitheater, in the area of the so-called temple, is once again being undertaken with the support of volunteers. To date, structures belonging to a porticoed public building in use between the mid- to late-Republican era and the third century AD have been discovered.

Catacombs
In 1999 excavations were carried out by the Pontificia Commissione di Archeologia Sacra in the catacombs of S. Vittoria, below the church of the same name, in order to make visits of the monument more safe and to expand the visitable area. At this time lamps of the type Bailey U-“Catacomb Lamps” datable between the fourth and fifth centuries AD were recovered.