An elliptical amphitheatre in the center of the city of Rome, Italy. Built of concrete and stone, it was the largest amphitheater of the Roman Empire, and is considered one of the greatest works of Roman architecture and engineering. The Colosseum is situated just east of the Roman Forum. Construction began under the emperor Vespasian in 70 AD. The Colosseum could hold, it is estimated, between 50,000 and 80,000 spectators, and was used for gladiatorial contests and public spectacles such as mock sea battles, animal hunts, executions, re-enactments of famous battles, and dramas based on Classical mythology.