The contours of the ancient stadium, built in the 6th century BC, are still visible in what is now a park in the shadow of the Palatine. Circus Maximus was primarily devoted to chariot races and was used for this purpose until around 550 AD. The stadium could seat up to 150,000 people. The original structure was built of wood. It burned down twice, on the second occasion starting the great fire when the Emperor Nero was said to have fiddled while Rome burned. It was in one of the tunnels here that Caligula met his end. Excavations began in 2009 at the east end of the circus and are likely to go on for some years.

The Circus Maximus (Latin for "largest circus"; Italian: Circo Massimo) is an ancient Roman chariot-racing stadium and mass entertainment venue in Rome, Italy. In the valley between the Aventine and Palatine hills, it was the first and largest stadium in ancient Rome and its later Empire. It measured 621 m (2,037 ft) in length and 118 m (387 ft) in width and could accommodate over 150,000 spectators. In its fully developed form, it became the model for circuses throughout the Roman Empire. The site is now a public park.