Great Drain

Early 5th century BC: Drain with width and breadth of 1 m., its side walls of polygonal masonry with a tiled bottom and large covering slabs. Its purpose was to convery to the Eridane River waste from the buildings of the Agora and rainwater from the surrounding hills. Its main channel crosses the west side of the Agora from south to north beneath the paving of the "West Street". At the beginning of the 4th century BC. two branches were added immediately south of the Tholos, one to the southeast and one to the southwest, to bring rainwater and waste from a broader section of the Agora into the main channel. In later antiquity the statue of the emperor Hadrian, set up on the "West Street" was used as a cover slab for the drain.