The arcade has three exits, but the one on the far right is blocked. I think this area would lead to the Coliseum. It would be a large building, with the inside housing the events on elavators. It would look like a smaller Arcade, and you would go down the elavators after paying the price to go down. There would be the same options there are currently, plus others like spectator (on another suggestion topic). To me, having a "physical" Coliseum in SK feels would be a lot nicer than a button on the top right (however, it could stay there for convenience).

Alternate Suggestion: Maybe the are to the right could be something else, like a station (trains? there are tracks there, but there could be a more advanced fantasy version of a train to fit the SK theme). This station would lead to one new area, and also intoduce a feature Iv'e seen a few people ak about: An area outside of Haven.

Final suggestion related to the Coliseum. What about a PvP chat channel, aka /3?