Chariot races were held in a circus, so named because of its circular shape. The oldest and largest circus in Rome was the Circus Maximus.
Originally there was no building, just a flat sandy track with temporary markers. As the popularity continued, the venue was improved over time to cater for the large crowds.
Spectators sat on the hills either side of the track. Gradually the area developed into a well-maintained stadium. Over time the wooden seating was replaced by stone.
Initial seating capacity was 150,000 spectators. This was continually enlarged until by 4th century AD the circus could provide seats for over 250,000 people (1/4 the population of Rome). By the time of Emperor Augustus, the entire building was over 600 metres long and about 150 metres wide.
In 329 BC, twelve starting stalls were built for the chariots at one end of the arena, and above this a platform for the magistrate responsible for the show. The Emperor’s palace was behind the Circus Maximus. He had a special box where he could sit without even leaving the grounds of the palace. Some emperors attended all of the races that took place.
Racing was so popular with the Romans that the last race was not held until 549 AD.
Circus Maximus in modern times. Today, the ring and some remains of the tiers can still be seen.
Note how tight the corner is at the end of the straight. Great skill would have been required to avoid crashes around the corners. Like with modern motor racing, this was what many of the race followers came to see.