Theatre of Dionysus, prototype of Greek theatres, situated on the south side of the Acropolis in Athens, in which all extant classical Greek plays were first presented. Development on the site began with the creation of the orchestra, a circular floor of earth 60 feet in diameter with an altar at the centre. Placed adjacent to temples of nature and of the fertility god Dionysus, the orchestra was used for dramatic performances, which, together with a procession and sacrifice, composed the annual spring festival of the god. During the 5th century BC, the theatre served as the locus of the contests in which the plays of Sophocles, Euripides, Aeschylus, and Aristophanes (which developed from the Dionysian tradition) were first performed. At the time, the auditorium, perhaps with wooden benches, was set into the hillside, and the skene, or building serving as the background of the play, was built on the opposite side of the orchestra.