For reference, the O.G. Bridgeport Arena:
That was pretty big for its time, but I think we need something
much bigger now. The original Arena had chests hidden under the sand with weapons and armor, and of course its successor needs something like that as well. If it's bigger, I also imagine building American Gladiator-style obstacles for taking cover, running around, etc.
I have had some recent ideas for continued expansion of Bradtropolis into that entire swamp region to the east. Maybe Arena 2.0 would go out there? Or maybe on the north side of the canal instead? Keeping it far from civilization, farms, or mass storage areas (i.e. places with lots of item frames, chests, hoppers, and signs) to keep participant FPS/performance high should be a key factor in deciding the location.
Hmmm... Now that I'm typing out these thoughts, I wonder if an
underground arena might work. It could have an ornate structure for an above-ground entrance, of course, but by digging down, it could sprawl out a far greater area without taking up precious surface land.