This figure is dressed in the thick, horizontally-banded tunic that charioteers wore as protective clothing. Chariot-racing was taken extremely seriously in Imperial Rome, and successful charioteers - and their horses - were treated like heroes. The contests took place in the circus, and two- or four-horse chariots came through starting gates to race seven times round a long, narrow course. The passion for chariot-racing evidently spanned all sections of Roman society, from the plebs urbanum who regularly filled the 150,000-capacity Circus Maximus, to the emperor himself. Teams were entered by private individuals, by the emperor, and by the 'factions' or supporters clubs. These passionately committed groups of supporters were known by their colours - Blues, Reds, Greens and Whites. According to the biographer Suetonius, the emperor Caligula (reigned AD 37-41) 'supported the Green faction with such ardour that he would often dine and spend the night in their stables and, on one occasion, gave the driver Eutychus presents worth 20,000 gold pieces.' (Caligula 55, 2f.). It has been suggested that this is a portrait of the emperor Caracalla (reigned 198-217) as a charioteer.