Other than stipulations regarding whether a race was for two- or four-horse chariots, there were no formal or consistent rules for chariot racing in antiquity. Between the start of the race and the 7th and final lap, anything was fair game. Although less violent than the gladiatorial games, chariot racing was still a very dangerous and often deadly sport.
Chariot races sometimes involved as many as 12 chariots at a time. The sand floor of the Circus Maximus, a large outdoor arena in Rome that measured almost a half mile in length, prevented lane designation, so drivers had to be astute. Lighter chariots won races, and it was not uncommon for collisions to result in drivers being tossed from chariots and subsequently trampled.
Chariots and their horses were usually owned by wealthy Roman citizens. Building the lightest and most efficient chariot was often costly. Because lighter chariots did not perform well in collisions, however, they frequently had to be replaced. Due to the dangers of the sport, chariot drivers were usually slaves or servants who, like gladiators, were specially trained in the sport. The spoils of the victory, however, usually went to the owner. It is believed that chariot racing was the sport that inspired the Olympic games.
In old times chariot racing was considered an olympic. Also they had no rules. The winner was the person who did not get slaughtered.
In Rome, it was called the Circus Maximus. It was on an oval track about the size of a football field. In Greece, it was the Hippodrome.