I've got even more bad news... the guys in the tower generally aren't ATC, but ground traffic control. The ATC guys will be in a dark room somewhere, probably a basement.
The guys in the tower are ATC, they do ground control (still ATC) and local control, surface to 2500' with a 5-mile radius. The dark room guys (TRACON) do surface to the top of their airspace (depends, 18k, 23k) with a 60-mile radius (roughly). Then there is center/en route, which does air traffic above the TRACON when you are level flying at 30k+.
