Colossal Coliseum is a new location that was added to Fortnite with the start of Chapter 2 Season 5. It is located next to the Zero Point location, which is in the center of the map.
Colossal Coliseum really is colossal, with a huge sand pit in the middle and tribunes around it. The Coliseum has 2 entrances, but you can always build yourself a staircase to climb it if needed. There are some statuses in the middle, such as a couple of llama horses or banana warriors.