The Colosseum or Coliseum, also known as the Flavian Amphitheatre, is an oval amphitheatre in the centre of the city of Rome, Italy. Built of travertine limestone, tuff , and brick-faced concrete, it was the largest amphitheatre ever built at the time and held 50,000 to 80,000 spectators. 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 . 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 an estimated 50,000 to 80,000 spectators at various points of its history over the centuries, 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.Although substantially ruined because of earthquakes and stone-robbers, the Colosseum is still an iconic symbol of Imperial Rome and is listed as one of the New7Wonders of the World. It is one of Rome’s most popular tourist attractions 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. In 2018, it was the most popular tourist attraction in the world, with 7.4 million visitors.The Colosseum is also depicted on the Italian version of the five-cent euro coin.

More details: https://en.wikipedia.org/wiki/Colosseum