This is the underground part where they kept all the Gladiators and animals that were about to fight. The Roman soldiers brought them up using elevators and they fought to the death. There was gladiator on gladiator, gladiator on animal, and animal on animal. Some of the gladiators were volunteers (hoping to get rich if they survived one year of fighting) but others were slaves forced to fight. If they refused to fight they were killed on the spot by the soldiers. pretty crappy huh?