Known also as the Flavian Amphitheater, commenced A.D. 72 by Vespasian, dedicated by Titus (80). The structure consists of four stories, each exhibiting a different order of architecture. Its form is that of an ellipse, 620 feet long, 525 wide, and 157 high. The arena was of wood covered with sand. There was a marble terrace reserved for privileged spectators, a special gallery for the emperor, tiers of seats for the ordinary citizens, and standing room for the lower classes. Probably about 45,000 could be seated. During the Middle Ages the Coliseum was used for a time as a stronghold by the Frangipani, and later came into the possession of the municipality of Rome. During four centuries great masses of its stone were taken for building material. In 1675 it was saved from demolition by Clement X, and from that time became a sanctuary on account of its connection with the martyrs. It is now a place of pilgrimage for visitors to Rome.