These images require some explanation. The Colisseum arena comprised a wooden floor covered by sand, covering an elaborate underground
structure called the hypogeum. Little now remains of the original arena floor, but the hypogeum is still clearly
visible in both images.

The hypogeum 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.