Sitting at 9,150 feet, the Mount Lemmon Air Force Station was said to be the world’s highest radar installation in 1957. It was manned by the 684th Aircraft Control and Warning Squadron, whose motto was “Who goes there?” Along with dozens of similar stations, it watched for Soviet aircraft before the advent of satellite surveillance. Nearly 250 officers staffed the 25-acre base, which featured a barracks with a “modern, electrically equipped kitchen.”