hypogeum
Noun
Meaning
The subterraneous portion of a building, as in amphitheaters, for the service of the games; also, subterranean galleries, as the catacombs.
Source: Webster's dictionarySynonyms
Derivatives
Examples
Arena and hypogeum The Colosseum arena, showing the hypogeum now filled with walls.
Detail of the hypogeum The hypogeum was connected by underground tunnels to a number of points outside the Colosseum.
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").
It has been suggested that the reports either have the location wrong, or that the Colosseum originally featured a wide floodable channel down its central axis (which would later have been replaced by the hypogeum).
Little now remains of the original arena floor, but the hypogeum is still clearly visible.
The depiction of the building itself is generally accurate and it gives a good impression of what the underground hypogeum would have been like.