ANCIENT CITY OF MEGALOPOLIS THEATRE AND ASSEMBLY HALL The south bank section of the city was the centre of the Arcadian League and the location of a theatre and an adjoining Thersilion (the league's assembly hall). With a capacity of 20,000, the theatre was one of the largest in the ancient world. Its auditorium, where the audience sat on benches made of limestone, was arranged on a natural hill. The first rows were reserved for dignitaries. North of the theatre is the square outline of the assembly hall and lots of fallen columns that once held up its roof. This building was a kind of parliament were serious decisions were taken on issues of war and peace.
Ancient city of Megalopolis Theatre auditorium

"The southern portion, on the other side of the river, can boast of the largest theatre in all Greece, and in it is a spring which never fails. Not far from the theatre are left foundations of the council house built for the Ten Thousand Arcadians, and called Thersilium after the man who dedicated it.."
Pausanias
Description of Greece
theatre