The Colosseum was a very large arena found on a far-off island. Since there was no bridge to walk to it, getting there proved to be a very difficult task.
The Colosseum was a downscaled replica of the real-world Colosseum. The outer rim of it consisted of a flat lounge area, while in the center there was a small fighting arena. The exterior of it was made up of arches, a staple of Roman architecture.
The Colosseum used to be behind the Ocean Missile Silo before getting moved to its own island.
The island the Colosseum rests on boasts the largest tree in-game.