I decided not to go for the Colosseum idea for the fight arena and kept it in theme with the animation.
I've gone for a minimalistic 'fight dome' concept and kept the exterior very blank and basic.
3 reasons for this:
1- The exterior would be almost blank since the whole thing is meant to be a simulation by a computer and the fight was never meant to breach the arena into un-constructed virtual space.
2- If I am to model the majority of this by myself, I might as well make up plot devices to make this easier for me ;-)
3- The electrified dome feels like it would fit with the whole omni-powerful computer and cyborg characters.