Megalopolis is a town located in the southwestern part of the regional unit of Arcadia in southern Greece. It occupies the same site as the ancient city of Megalopoli, which was established in 371 BC.
The settlement is notable for being the first large urbanization in rustic Arcadia. During antiquity, it featured a theatre with a capacity of 20,000 visitors, making it one of the largest theatres of ancient Greece.