Arena and hypogeum
How big is the Roman Collosseum?
Colosseum
The arena itself was 83 meters by 48 meters (272 ft by 157 ft / 280 by 163 Roman feet). It comprised a wooden floor covered by sand (the Latin word for sand is "harena" or "arena"), covering an elaborate underground structure called the "hypogeum" (literally meaning "underground"). Little now remains of the original arena floor, but the "hypogeum" is still clearly visible. It consisted of a two-level subterranean network of tunnels and cages beneath the arena where gladiators and animals were held before contests began. Eighty vertical shafts provided instant access to the arena for caged animals and scenery pieces concealed underneath; larger hinged platforms, called "hegmata", provided access for elephants and the like. It was restructured on numerous occasions; at least twelve different phases of construction can be seen. The "hypogeum" was connected by underground tunnels to a number of points outside the Colosseum. Animals and performers were brought through the tunnel from nearby stables, with the gladiators' barracks at the Ludus Magnus to the east also being connected by tunnels. Separate tunnels were provided for the Emperor and the Vestal Virgins to permit them to enter and exit the Colosseum without needing to pass through the crowds. Substantial quantities of machinery also existed in the "hypogeum". Elevators and pulleys raised and lowered scenery and props, as well as lifting caged animals to the surface for release. There is evidence for the existence of major hydraulic mechanisms and according to ancient accounts, it was possible to flood the arena rapidly, presumably via a connection to a nearby aqueduct.