Short answers, pulled from the story.
The Circus Maximus measured 621 meters in length and 118 meters in width. It could accommodate over 150,000 spectators, making it the first and largest stadium in ancient Rome and its empire.
The Circus Maximus hosted beast-hunts (venationes), gladiator fights, athletic competitions, plays, recitals, public executions, and religious processions. A venatio in 169 BC employed 63 leopards, 40 bears, and elephants. Long-distance foot races were still held there even after the Stadium of Domitian opened for track athletics.
The last known races at the Circus Maximus were held by Totila in 549. The last known beast-hunt at the site took place in 523.
The Circus Maximus was Rome's primary venue for ludi, public games tied to religious festivals. It contained shrines to Murcia, Consus, Hercules, and later the Sun-god, whose obelisk stood on the central barrier. The Sun-god was the divine patron of the Circus and its games in the Imperial era.
After the sixth century the Circus fell into disuse and was gradually buried under waterlogged soil; the original track now lies six meters beneath the modern surface. By the eleventh century it housed dwellings, and by the sixteenth century it served as a market garden. In 1852 a gas works was built on the site, remaining until 1910. Today it is a public park.
Augustus repaired fire damage from 31 BC and erected Rome's first obelisk, brought from Heliopolis in Egypt, on the central dividing barrier of the Circus. He also built a monumental pulvinar, an elevated imperial shrine raised above the trackside seats, from which he sometimes watched the games alongside images of the gods.