As Ludi Circenses, games with chariot racing, were religious events, the day started with an elaborate religious procession, the pompa circensis, where the gods were brought from the Capitoline and other locations so they could enjoy the racing too. The parade involved dancers, music, officials – and the horses which were to race. (The horses themselves could be celebrities, just like the charioteers.)
Races were normally of two horse or four horse chariots which raced seven laps in total, although other combinations were possible (including camel and elephant racing); there were 24 races in the day. The factions normally raced against each other, although they might team up and compete that way (so two factions would compete against two other factions). Because the level of dust was such that it obscured the charioteers’ vision, they were led around the course by horseback riders, who guided them along the course. Races began when the official in charge of the games (often the emperor) dropped the mappa, a napkin, to signal that the horses could leave their starting gates.