Aside from its massive size-615 feet long, 510 feet wide, and 159 feet tall-some of the features of the Colosseum that make it particularly impressive are features that are hidden. Beneath the building was a complex system of tunnels and rooms where animals and performers waited to enter the arena. Archaeologists also believe that water system beneath the Colosseum made it possible for the Romans to flood the arena and stage water battles. Today, some of the underground structures are visible because the original arena stage floor is
