Blogger under the nickname Sekiro Dubi revealed the secret of the big arena in Elden Ring. In his opinion, a structure like the Colosseum was created for the battles of players against monsters.
To understand the question, Sekiro Dubi studied the game files and read the description of some items. This led him to believe that the arena had been used in the Interearth past long before the time of Radagon.
By changing the settings, the blogger launched the battles of huge monsters, and also found a new place of grace in the Colosseum. It is interesting that the enemies immediately attacked the character, and after that they began to fight among themselves.
First Colosseum discovered FromSoftware game researcher Lance McDonald. Dataminer shared the find and suggested that the arena could be designed for online battles between players.