The arena is a pretty big place with multiple big halls, where rings are placed so multiple matches can take place at once. The Ring is normally a standard issue wrestling ring unless provisions are made for new and proposed wrestling rules or match styles, but generally there's plenty of room to run around and jump and do crazy things. The ring is always exactly as sturdy as it [i]needs[/i] to be. As in, if you [i]need[/i] to piledrive someone through the floor and fall into the hidden stockpile of barbed wire bats and steel chairs, take it up with your opponent, and if they're okay with that, then it shall be so. The ring can also change in settings outside of the Arena. If you need to, say, wrestle in the semi-hollow remains of a big tree, or through some feat of magical bedevilry, become a giant and fight inside the Stonehenge, that's your prerogative.