A Stoa at the South of agora, the seat of the local Boule (parliament)
Initially, the edifice had an "U" shaped plan, comprising three wings and a colonnade opening to the Agora. At the turn of 4th to 3rd century BC a second stoa was added at a lower level to the south connected to the older one through stairways. A room built at the east side during 2nd century AD most probably was dedicated to the worship or to man emperors.
The use of the building for civic purpose rests on several inscriptions of a political nature (that where) found in or near it. The bouleuterion at Mantineia is a rare example of a stoa used for housing an assembly.