"Who goes there" was the motto of the 684th Aircraft Control and Warning Squadron manning the Mt. Lemmon Air Force Station in 1957. The installation, at 9,150-feet, was said to be the world's highest radar installation. Along with dozens of other similar stations, it watched for enemy Soviet aircraft approaching the U.S. before the advent of satellite surveillance.

Nearly 250 officers staffed the 25-acre base, which featured a barracks with a "modern, electrically equipped kitchen," according to a Tucson Citizen story in 1957.

For pictures of the base in 1957, go to tucson.com/retrotucson