The Colosseum 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 was built with the spoils of the sack of the Jewish temple in Jerusalem. An ancient inscription was found read: "Imp. T. Caes. Vespasianus Aug. Amphitheatrum Novum Ex Manubis Fieri Iussit." (The Emperor Caesar Vespasian Augustus had this new amphitheatre erected with the spoils of war.) There is no doubt what war this was, the sack of Jerusalem. (source: Biblical Archaeology Review)
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. Christians were fed to hungry lions and burned alive here for Romans' entertainment.
Admission and food was free to the ancient Romans who attended the events held there.
Some of the events and games that were held in the Colosseum lasted for up to 100 days.
They Romans had the earliest form of a Skydome. If it rained they stretched a red canvas over the entire Colosseum.
In the early medieval era it was no longer used for entertainment purposes. Eventually it was used for workshops, housing, religious quarters, a quarry, a fortress and even as a Roman Catholic shrine.
After the Colosseum was partially destroyed by the earthquake, some of the fallen pieces were used to build St Peter's Basilica.
The Colosseum is one of the most popular Roman tourist attractions today.
Ray Charles, Paul McCartney, Billy Joel and Elton John have all performed concerts at the Colosseum.