In the background of Colorado Springs, Pike’s Peak dominates the sky. But just to that mountain’s southeast looms another geological ripple. Cheyenne Mountain—a rounded, rocky thing that rises 9,565 feet above sea level—looks wild and quiet. But deep inside the mountain, a crew of humans toils in one of the nation’s most secure military installations.

Learn about your ad choices: dovetail.prx.org/ad-choices