HIPPODROME, a Greek building for horse and chariot races, corresponding to the Roman circus. It was usually placed on a hill slope, so that the excavated material from one side could serve for an embankment for the other. One end was semi circular and the other square. The seats ran continuously around the semi-circle and the two long sides, in rising tiers, and down the centre was a division. Owing to the fact that as many as ten chariots raced at a time, a width of about 400 ft. was necessary. The usual length varied from 600 to 700 feet. Many remains of the hippodrome at Constantinople exist, and are now (1928) being carefully investigated. In this case much of the area was supported on tiers of great vaults instead of the more usual em bankment. On the centre division, between an Egyptian obelisk and a memorial column, was placed the famous bronze serpent tripod from the oracle at Delphi. These three monuments still exist in place. Begun by Severus in 203, and completed by Con stantine in 33o, it was both the largest and the most splendid hippodrome of the ancient world. Among its decorations were the f our Greek bronze horses that now stand on the facade of St. Mark's at Venice.