Ancient Theatre of Megalopolis

Built c. 370 BC as part of the founding of Megalopolis, capital of the Arcadian League established to counter Sparta. With a 131-meter diameter cavea and capacity of 20,000 spectators, it was among the largest theatres in ancient Greece. Adjacent stood the Thersilion, a massive assembly hall (66 x 52 m) with 65 columns that could seat 8,700 people, whose Doric portico served as the theatre's scene building.