When was the Colosseum built?

The Colosseum, originally called the Flavian Amphitheatre after the ruling dynasty, was built on the site of an artificial lake in the grounds of the palace of Nero. It measures about 189 metres long and 156 metres wide and could hold an estimated 50,000 to 80,000 spectators. Titus opened it in AD 80 with games that lasted 100 days, including gladiator fights and animal hunts. Its builders used travertine stone, tuff, brick and Roman concrete, and a complex system of underground tunnels called the hypogeum was added later under Domitian. Earthquakes and stone robbing damaged it over the centuries, but it remains the largest ancient amphitheatre ever built.