The most complete Greek theatre, and the only one to preserve any real semblance of those used by Aeschylus, Sophocles and Euripides, is that of Epidauros, near Athens, built about 350 BC. The oldest feature is the orchestra, the round dancing floor of the chorus. There was probably some form of skene, but the present remains do not enable us to reconstruct it. The plan  shows the theatre as it looked in the second Century BC with a permanent skene, a stage (proskenion, i.e. in front of the skene) and ramps leading up to it.

IN: Tidworth, Simon : Theatres: An Illustrated History. London 1973 p. 10

One of the largest Greek theatres measuring almost 120 m from the orchestra up to the final row of seats in the auditorium, holding up to 12,000 spectators. The acoustics are remarkable in this theatre . The shape of the auditorium is more than a half-circle. The orchestra still has a circular shape.