It is also known as the Flavian Amphitheatre because it was built during the Flavian dynasty. It got the name Colosseum because of a statue that was located alongside the amphitheatre called ‘the colossus of Nero'. Construction began in 72 AD under the emperor Vespasian. Titus, Vespasian's son and successor completed the construction in 81 AD. It took only 9 years to build. Even today, construction of a stadium that size would be difficult to build in only 9 years. It took 60,000 Jewish slaves to build the Colosseum. It was built of stone and concrete. Domitian, Vespasian's youngest son, made modifications to the amphitheatre during his reign from 81-96 AD. He built underground tunnels to hold slaves and animals. He also built a gallery to the top for additional seating. Several different events were held in the Colosseum including gladiator contests, mock battles and animal hunts, and dramas that were based on Classical mythology. If they held a mock sea battle they flooded the Colosseum with water. There were also re-enactments of famous battles and executions held in the amphitheatre. The amphitheatre was used for entertainment for 390 years. During this time more than 400,000 people died inside the Colosseum. It's also estimated that about 1,000,000 animals died in the Colosseum as well.