The Colosseum is an oval amphitheatre in the centre of the city of Rome, Italy. Built of travertine, tuff, and brick-faced concrete, it is the largest amphitheatre ever built. The Colosseum is situated just east of the Roman Forum. Construction began under the emperor Vespasian in AD 72, and was completed in AD 80 under his successor and heir Titus. Further modifications were made during the reign of Domitian (81-96). These three emperors are known as the Flavian dynasty, and the amphitheatre was named in Latin for its association with their family name.

The Colosseum could hold, it is estimated, between 50,000 and 80,000 spectators, having an average audience of some 65,000.  It was used for gladiatorial contests and public spectacles such as mock sea battles, animal hunts, executions, re-enactments of famous battles, and dramas based on Classical mythology. The building ceased to be used for entertainment in the early medieval era. It was later reused for such purposes as housing, workshops, quarters for a religious order, a fortress, a quarry, and a Christian shrine.

After four centuries of active use, the magnificent arena fell into neglect, and up until the 18th century it was used as a source of building materials. Though two-thirds of the original Colosseum has been destroyed over time, the amphitheater remains Rome's most popular tourist attraction and also has links to the Roman Catholic Church, as each Good Friday the Pope leads a torchlit "Way of the Cross" procession that starts in the area around the Colosseum.

The Colosseum is also depicted on the Italian version of the five-cent euro coin.