The Colosseum was built in eight years, 72 AD to 80 AD, in Rome, Italy during the reign of Roman Emperor Vespesian.
It had seating for 50,000 people and was designed with 76 different entrances each with their own seating areas for effective crowd control.
The Romans invented concrete and used it for the massive foundation which was an oval ring of concrete 167 feet (51 meters) wide and 40 feet (12 meters) deep.
A special ten-mile road was constructed from the quarry to the building site to accommodate 292,000 cartloads of stone needed to build the Colosseum.
Massive wooden frames were used to support the arches and vaults until all the stone parts were in place.
Huge linen veleriums hung from poles and ropes at the upper most levels and were moved by sailors to keep the audience protected from the hot sun.