Yes, a large expanse of wall is a tempting thing for we map-addicted. One of the first offices I worked in alone had a huge expanse of blankness... soon nicely mappified by a mosaic of about 5 x 7 USGS 1:24,000 topo quads of Colorado mountains. :-)
Hey, don't simplify yuour arena too terribly much......... a simple pit in the wilderness would do for Just Fightin' ... no, you need the pens where various animals are kept, the vast swath of spectator seating, the prominent spot for the prominent citizen to give thumbs up or down, the section for the brass band or bagpipe chorus, the fried weasel-on-a-stick vendor carts, the armory, the gladiator dorms or cells, the guardposts, the moneychangers and bettor corner, the VIP balcony, the rodeo clown barrels, the crumbled wall where in '26 the Bogniferian Contingent mounted and tried to take over the stands, before being smitten by a convenient bit of directed lightning (one only THINKS those lightning rods atop the walls are fore protection - HA), the Ford and Chevy dealership adverts on the walls, and on and on. Small town? Well, maybe only a Ford dealer, and only one guy with a tuba instead of The Massed Pipes. Still ....
INteresting possibilities, an arena.
Anyway - can't wait to see what you come up with!