The Greek open-air theater was first a circular, flat orchestra pit located in the hollow between two hillsides. In 465 B.C. a small wooden hut called a skene (hence, scene), in which the actors changed costumes, was erected behind the playing area. When stone structures were erected the seating area was cut to little more than a semicircle and the skene became a two-story building with three doorways in front and an entrance by either side. It thus served additionally as the scenic background of the play. The floor in front of the skene was elevated, with steps leading down to the orchēstra, where the chorus was located; this narrow playing level was called the proskenion (hence, proscenium).