The theatre at Thorikos, Lavrio is the most ancient theatre to be preserved in Greece. The earliest phase of its construction is Archaic, i.e. dating to the late 6th century BC. It is elliptical in shape, as is its orchestra, like a rectangle with rounded corners rather than the usual semicircle. (source).
Canon EOS DIGITAL REBEL XTi, 01/03/2008, Shutter Speed 1/200, Aperture Value 7.1, ISO 100, Lens EF24-70mm f/2.8L USM, Focal Length 24.0 mm