Building or space in which a performance is given to an audience, an important adjunct of most Greek and Roman towns. In ancient Greece, where theatre began in the 5th century BC, the theatres of the classical period were constructed between two hills (essentially D-shaped) so that the audience sat in a tiered semicircular arrangement facing the orchestra circle, in which most of the action took place. (The name amphitheater should be used only of a circular or oval structure in which the seating completely surrounds the stage, as in the Colosseum). Greek theater consisted of two main elements: the orchestra, a space for acting and dancing which was usually circular; and the auditorium, a spectators' area, which was probably no more than a hillside or slope originally. Later, the skene (originally perhaps only a temporary structure for the convenience of performers) was added. Well-preserved examples survive at Epidaurus, Pompeii, and Orange.