The Bouleuterion is connected to the South Agora and has a diameter of 35 m, including the surrounding wall. The diameter of the south facing cavea is 30m. Although it was later used as a quarry, it has been severely destroyed, but remains of 7-8 rows of marble seats are still preserved. The existing rows of seats bear letters, which indicates that the building was used as a town hall and as an odeon.
The building dates from the reign of Emperor Hadrian (117-138 AD). It had a capacity of 500 - 600 people.