The word Hypogeum literally means “underground” from the Greek words hypo (meaning under) and gaia (meaning earth). The Hypogeum of the Colosseum refers to the vast network of rooms, cells, tunnels and passages under the Roman Colosseum.
The entire base or area of the Roman Colosseum measured 6 acres. The hypogeum was easily able to accommodate a vast a series of underground tunnels, passages and chambers used to house animals, stage props and the slaves who had to work there. The hypogeum consisted of two-level subterranean network of tunnels, shafts, mechanical devices and 32 animal pens. The tunnels led to other buildings outside the structure of the Colosseum.