Square building, probably a Bouleuterion, dating back to the end
The interior of the building consisted of two small rooms, probably used as offices and archives. In the room to the south was an interior collonade, an altar in the centre, and an exedra (podium) facing the altar, all bearing great resemblance to typical architectural elements of other known bouleuteria. The wooden seats arranged on the west side of the room provided for a seating capacity of 250.
The building was presumably used for storing standards of weights and measures, or even as an arms depot. Latest research questions its use as a bouleuterion, identifying it with the prytaneion.