We've previously featured Garden of Eyes' modding work before, they're also among the modders accountable for digging through the game's code and revealing the location of "three doors that aren't openable in Elden Ring Runes the colosseum," that many are thinking could be the basis of an update that will be released in the near future.
YouTuber Garden of Eyes wasn't the first to release a video about these hidden locations however, their video provides a lot of detail on the coliseums of Leyndell, Northern Limgrave, and Caelid. Each of these locations is completely constructed and have colliders that determine the extent to which your character is able to slide through certain objects.
The video shows you will observe the modder's Tarnished breaking several jars when he runs into them. In the middle of the corridors, you will find a fully-constructed colosseum with a multitude of seats. In Elden Ring Runes buy the event that the Lands Between weren't a barren desert, it would have been the perfect spot to showcase your boss-killing abilities.