Races on horseback date from the thirty-third Olympiad. Philip of Macedon won in this contest, and celebrated his victory by having an enormous horse, ridden by a diminutive jockey, placed on his coinage. As this victory took place in the same year in which Potidaea fell into his hands and his son Alexander was born, he regarded that year as especially auspicious.
While the race of the quadrigæ of horses was introduced as early as the twenty-fifth Olympiad, that of the bigæ of horses was not introduced until the ninety-third Olympiad. A quadriga consisted of four horses harnessed to a chariot; a biga, of two horses. In the seventieth Olympiad, bigæ of mules were admitted, but in the eighty-fourth Olympiad they were excluded; their exclusion may be ascribed to two reasons: first, they presented an unpleasing appearance; second, among the Eleians, according to Pausanias, a curse had rested on the animals from ancient times.
Prior to the twenty-fifth Olympiad, all athletic contests had taken place in the Stadion. As chariot-racing, however, demanded more room, a separate race-course, called the Hippodrome, was established. The site of the Hippodrome cannot be exactly traced. This is because the Alpheios has washed away all certain indications of its limits. But from the account of Pausanias (V, 4; VI, 20, 7 foll.) it may be approximately located; it lay to the south of the Stadion and extended roughly parallel with it, though stretching far beyond it to the east. The German explorers who excavated Olympia inferred from the state of the ground that the Hippodrome was about 2526 feet in length. The Stadion and Hippodrome were closely connected, the rear part of the aphesis, or starting point, of the Hippodrome adjoining the end of the Stadion. At the farther end of the Hippodrome was the goal outside of which the chariots had to turn. To round this goal with advantage, that is, to keep as close to it as it was possible to do without upsetting his own chariot or colliding with another, required long practice and great dexterity on the part of the driver; it was indeed a very dangerous feat; at every race a large number of the chariots involved were wrecked, and in such accidents the charioteers rarely escaped without serious injuries. According to legend, Orestes had met his death at a Pythian festival; his chariot colliding with the goal, he fell to the ground, became entangled in the reins, and was dragged or trampled to death. After every turning of the goal, the chariots were greeted with the sound of trumpets in order that men and horses might attain new courage and vigor after so dangerous an ordeal.