A possible location for the Antitower is in the Sea of Clouds. You know how when you log in to a region, you see beautiful artwork? When you log in to any zone in Abalathia's Spine, You see a picture of a large upside down castle on the underside of one of the islands, which is currently not accessible in game. If it isn't going to be used in game, why would they not only make the artwork, but put it in so prominet a viewing location anytime someone logs in?