How many years did it take to build the Colosseum?

It took about 8 years to build the Colosseum, from roughly AD 72 to AD 80.

Emperor Vespasian began construction of the amphitheatre around AD 70–72, during the Flavian dynasty. His son Titus completed the main structure in AD 80, soon after becoming emperor. The speed was remarkable for a huge building made from travertine limestone, tuff, brick-faced concrete and other materials.

The figure is an approximation because ancient sources do not provide a modern construction schedule, and some finishing work continued afterward. Emperor Domitian later added important features, including the underground hypogeum beneath the arena. That means “eight years” refers to the main construction period, not every later alteration.

A common mix-up is the claim that the Colosseum took ten years. That version usually counts from AD 70 to AD 80, while the commonly cited account dates the organized construction from about AD 72. The inaugural games were held in AD 80 or 81.