Colosseum, Rome. The Colosseum or Flavian Amphitheater was begun by Vespasian, inaugurated by Titus in 80 AD and completed by Domitian. ^^^Located on marshy land between the Esquiline and Caelian Hills, it was the first permanent amphitheater to be built in Rome. Its monumental size and grandeur as well as its practical and efficient organization for producing spectacles and controlling the large crowds make it one of the great architectural monuments achieved by the ancient Romans. The Colosseum was designed to hold 50,000 spectators, and it had approximately eighty entrances so crowds could arrive and leave easily and quickly.