MEGALOPOLIS ANCIENT CITY OF MEGALOPOLIS Spreading extensively on both banks of the Helisson river just above its junction with the sacred Alpheios river, is the ancient city of Megalopolis. It was founded on a grandiose scale (371-368 BC) by Epaminondas of Thebes as the seat of the Arcadian League and a bastion against Spartian imperialism. The city was protected by nine kilometres of city walls and occupied by the inhabitants of approximately 40 abandoned Arcadian villages. South of the river was the centre of the Arcadian League with a theatre and assembly hall. To the north was a marketplace flanked by civic buildings.