The Poseidome Colosseum
is the Colosseum of Atlantis
. King Neptune
, and SpongeBob SquarePants had a Cooking Contest in this building in the episode Neptune's Spatula. It also appears in Battle for Bikini Bottom, where Robo-Sandy is the Boss.
It is a large concrete, Greek Building, with large concrete cylinders at the main entrance. inside there is a modern arena, with Show lights, a Ring, and many rows of viewing seats.