You will exclaim “wow” repeatedly as you walk inside the Colosseum. The 272 foot by 157 foot arena once accommodated 50,000 up to 80,000 people. The stone passageway in the center is called a hypogeum. This was a highly sophisticated, underground system used to reset stage props and channel gladiators and animals into the amphitheater. When scheduled to appear, they were raised into position using elevators, pulleys and hydraulic lifts. The arena could also be flooded for mock naval battles. The hypogeum was covered with a wooden base similar to the one in the photo and then blanketed with a layer of sand.