Mount Laguna Air Force Station, California

Mount Laguna Air Force Station is located atop Mount Laguna, with a steep drop into the Anza-Borrego desert. The base was originally designed as a GCI (ground-controlled interception) site, whose purpose was to determine (using radar), whether an aircraft was friendly and if not, to help guide interceptor aircraft to the target. Several hundred people worked there in its heyday, until it was downsized in 1981.  Now it is a multi-use satellite and radar communications site, operated primarily by the FAA, out of Los Angeles Center. In 2012, the U.S. Forest Service embarked on a project to raze all remaining non-FAA buildings, remove all hazardous waste, and ultimately allow the site to return to its natural state. Completion is expected to take several years.