"The Theatre, Epidauros, designed by Polycleitos, was the most perfect development of the theatral form. The principles of designing to perfection experienced in building temples were applied to the theatre. Geometrical exactitude of layout was accompanied by variations and adjustments in response to human requirements: only the central two-thirds of the seating is concentric with the circle of the orchestra, and the seats nearer the parados were arranged with a slightly flatter curve as a concession to easier sight lines. The section of the cavea was also designed with proper regard for sight lines, the upper part outside the gangway (diazoma) being at an angle steeper than the lower part. The orchestra, a complete circle, is 20.4 meters (67 feet) in diameter, and the overall diameter of the theatre is 118 meters (387 feet). The lower cavea has 34 rows of seats, separated from the upper cavea of 21 rows by the diazoma. 'Parodoi' forming entrances at orchestra level separate the cavea from the skene reconstructed about 200 B.C.E. Sloping ramps, starting from outside the simple stone gateways, led to a high proscenium, providing a stage about 3 meters (10 feet) deep, faced with an Ionic colonnade and having projecting wings or parascenia at the ends."
Palmes, J. C. (1975). Sir Banister Fletcher's A History of Architecture (18th Edition). New York: Charles Scribner's Sons. p. 243.