The Roman theatre from the 1st century A.D. forms an architectural unit with the immediately adjoining stadium. The lower parts of the cavea, the ima cavea, were built on a slope, while the upper parts were built on substructures. It consists of 23 rows of seats separated by a diazoma from the media cavea, the middle tier. The rows of seats of the summa cavea rest on a vaulted ceiling that could be reached from the outside by stairs. From this corridor one reached the diazoma between the lowest and middle levels.

The originally single-storey stage house, like parts of the cavea, was renovated and extended at least twice until the 3rd century. The marble cladding of the stage house with fragments of a hunting frieze had fallen down in the orchestra for centuries.

According to the founding legend, Aizanoi was founded by Arcadian settlers. The archaeological evidence of a settlement dates back to the 3rd millennium B.C., but a more extensive settlement was not established until the Hellenistic period. Around 200 B.C. the area in which Aizanoi lies came to the kingdom of Pergamon as Phrygia epiktetos ("acquired Phrygia"); at times it also belonged to Bithynia. The Pergaman kings settled mercenaries who probably came from Macedonia. Together with its entire empire, the city entered the Roman province of Asia after 133 BC.

Aizanoi experienced a great boom in the early imperial period. In particular, numerous public buildings were erected, such as a temple of Artemis Hagiotate in the middle of the 1st century A.D., and before its end the sanctuary of Zeus, the main god of the city. It is largely preserved.

Important construction works in the city are connected with a rich family of the city, especially Ulpius Appuleianus Flavianus and his son Ulpius Appuleius Eurycles. Eurycles was also an emissary to the Panhellenion in Athens, which Hadrian had established.
During this time, a large bathing and gymnasium complex and a water pipe leading to it were also built.
Further public buildings were a circular building, which served as a macellum (market building) and to which a copy of Diocletian's highest price edict was attached, and a late antique (around 400 AD) column road.