Probably the best high-security story I've heard came from my brother who wrote consumer loans in Omaha. He knew this guy who did regular maintenance on Xerox machines including one at SAC headquarters beneath downtown Omaha. Of course he had to have clearance. On each visit, they would inspect him and his tools and take him on an elevator ride down to the secure part of the facility. Then they would go down this long dark hallway. At the end of the hallway, under a single bare bulb was the machine. The repairman commented once that maybe the machine would be of more use if the light was better. The reply was that, "You don't understand, we build this hallway just for you when you visit. In two hours, this hallway won't be here and the light will be better."