Turns out I studied history in college and my final work was done on Roman gladiatorial games. ;) 

It doesn't really matter, but not all Arenas were what people expect them to be. The vast majority of them were small.

[i]Actual [/i]Arenas (let alone the Coliseum) were not a very common things. Often, people organizing the games would just use the public square of the city and turn it into a kind of arena by having everyone find a place around it and that was it. 

For a medieval city like this, I'd have to imagine it'd be relatively small. Politics changed and gaining favor of the wide public wasn't as important. In the feudal system only nobles and religious authority really mattered to please. So they'd probably be the only one to be invited, hence a smaller more enclosed arena. 

RP-wise, that could also provide the perfect opportunity for Noble characters to meet common ones from either the hunter's guild or anywhere else. 

I found two pics if you want - maybe you already seen them. ;) Nothing fancy, just general ideas of what it could look like

[hider][img]https://slm-assets0.secondlife.com/assets/3463415/view_large/Snapshot_025.jpg?1303984872[/img][/hider]
[hider]https://i.pinimg.com/474x/bc/a5/9b/bca59b820e3049ca30a17a4a13d3df85--gladiator-arena-god-of-war.jpg[/hider]