<P> Another level, the maenianum secundum in legneis, was added at the very top of the building during the reign of Domitian . This comprised a gallery for the common poor, slaves and women . It would have been either standing room only, or would have had very steep wooden benches . Some groups were banned altogether from the Colosseum, notably gravediggers, actors and former gladiators . </P> <P> Each tier was divided into sections (maeniana) by curved passages and low walls (praecinctiones or baltei), and were subdivided into cunei, or wedges, by the steps and aisles from the vomitoria . Each row (gradus) of seats was numbered, permitting each individual seat to be exactly designated by its gradus, cuneus, and number . </P> <P> 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"). The hypogeum was not part of the original construction but was ordered to be built by Emperor Domitian . 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 . </P> <P> 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 . </P>

What is on the floor of the colosseum