This is a spleef arena with two stone generators, each sitting at 24 blocks long and on opposite sides of the platform. This puts the platform at 24x24 blocks. The arena also comes with a circle with seats for spectators which is connected to the arena by large deepslate and stone brick chains.

Use this video in order to put the structure in your own minecraft world:https://www.youtube.com/watch?v=3T8LhO7EKq8