The Civil Town amphitheatre, the smaller of Aquincum's two amphitheatres, lies beyond the northern wall of the town.
The building, already in operation in the mid-2nd century, was renovated multiple times during the 3rd century. Based on its structure, the almost circular building (its axes are: 86.5m x 75.5m) can be classified as an earth amphitheatre. In such amphiteatres the slope for seats was created by ramming earth between two ring walls. The stone benches of spectators were placed on this, some of which carried the inscribed name of their owner. The roughly 6-7000 spectators could enter the partially-covered stands from a ramp on the outside. The arena, which was surrounded by a 3-metre-high wall, could be entered through a gate on either side of the east-west axis.
The amphitheatre held various sporting events and gladiatorial games mixed with animal hunts. Since this building had the largest capacity in the town, it was also used for more serious public business. It hosted assemblies and civic festivals as well as speeches in honour of the visiting emperor. The gladiator barracks were located by the amphitheatre, where the champions of the popular games exercised and trained. Its courtyard, surrounded by a stone wall, and its tower are now below ground. On the southern side of the western gate stood a sanctuary of Nemesis, the goddess of amphitheatre games. During the excavation of the sanctuary, a fragment of the goddess’s statuette was found along with a number of inscribed altars.