The hypogeum (literally meaning “underground”) was a later addition to the Colosseum. It consisted of a two-level subterranean network of tunnels and cages beneath the arena where gladiators and animals were held before contest began. It was connected by tunnels to a number of points outside the Colosseum. Animals and performers were brought through the tunnel from nearby stables. Elevators and pulleys raised and lowered scenery and props as well as lifting caged animals to the surface for release. There are some accounts that this area could be flooded to reenact naval battles.