Colosseum, also called Flavian Amphitheatre, giant amphitheatre built in Rome under the Flavian emperors. Construction of the Colosseum was begun sometime between 70 and 72 CE during the reign of Vespasian. It is located just east of the Palatine Hill, on the grounds of what was Nero’s Golden House. The artificial lake that was the centrepiece of that palace complex was drained, and the Colosseum was sited there, a decision that was as much symbolic as it was practical. Vespasian, whose path to the throne had relatively humble beginnings, chose to replace the tyrannical emperor’s private lake with a public amphitheatre that could host tens of thousands of Romans.