circensis) that ended at the venue. Competitive events were held also in smaller venues such as the amphitheatre, which became the characteristic Roman spectacle venue, and stadium. Greek-style athletics included footraces, boxing, wrestling, and the pancratium. Aquatic displays, such as the mock sea battle (naumachia) and a form of "water ballet", were presented in engineered pools. State-supported theatrical events (ludi scaenici) took place on temple steps or in grand stone theatres, or in the smaller enclosed theatre called an odeon. Circuses were the largest structure regularly built in the Roman world, though the Greeks had their own architectural traditions for the similarly purposed hippodrome. The Flavian Amphitheatre, better known as the Colosseum, became the regular arena for blood sports in Rome after it opened in 80 AD. The circus races continued to be held more frequently. The Circus Maximus could seat around 150,000 spectators, and the Colosseum about 50,000 with standing room for about 10,000 more. Many Roman amphitheatres, circuses and theatres built in cities outside Italy are visible as ruins today. The local ruling elite were responsible for sponsoring spectacles and arena events, which both enhanced their status and drained their resources. The physical arrangement of the amphitheatre represented the order of Roman society: the emperor presiding in his opulent box; senators and equestrians watching from the advantageous seats reserved for them; women seated at a remove from the action; slaves given the worst places, and everybody else packed in-between. The crowd could call for an outcome by booing or cheering, but the emperor had the final say. Spectacles could quickly become sites of social and political protest, and emperors sometimes had to deploy force to put down crowd unrest, most notoriously at the Nika riots in the year 532, when troops under Justinian slaughtered thousands. The chariot teams were known by the colours they wore, with the Blues and Greens the most popular. Fan loyalty was fierce and at times erupted into sports riots. Racing was perilous, but charioteers were among the most celebrated and well-compensated athletes. One star of the sport was Diocles from Lusitania (present-day Portugal), who raced chariots for 24 years and had career earnings of 35 million sesterces. Horses had their fans too, and were commemorated in art and inscriptions, sometimes by name. The design of Roman circuses was developed to assure that no team had an unfair advantage and to minimize collisions (naufragia),