Ancient Agora. Athens. Greece. View of the Great Drain, dating from the early 5th century BC at the Agora. Constructed of polygonal limestone, the Great Drain was created to channel the rainwater which flowed down from the hills on the southwest including the Acropolis and Aeropagos into the Eridanos River. The Agora from 600 BC onwards was the commercial and social centre of Ancient Athens. It was here that laws were written and displayed, commercial goods bought and sold, intellectual discussions were had, and the democratic spirited was born and nurtured.