There is a place in the Nevada desert the size of Belgium that doesn't officially exist. It is the airbase where test flights of our top-secret experimental military aircraft are conducted and —not coincidentally—where the conspiracy theorists insist the Pentagon is hiding UFOs and aliens. This is Dreamland—or Area 51. For Phil Patton, the idea of writing a travel account of a place he couldn't actually visit was irresistible. What he found was a world where Chick Yeager and the secret planes of the Cold War converged with the Nevada Test Site and alien landings at Roswell.A think tank for aviation engineering, Dreamland can be seen from a summit outside the base's perimeter, a hundred miles north of Las Vegas. On Freedom Ridge, groups of airplane buffs gather with their camouflage outfits and binoculars. These are the Stealth chasers, the Skunkers, guys with code names like Agent X and Zero,...