CORKSCREW was one of several presidential emergency facilities and related communications relay stations constructed in the early 1960s in the Washington, DC region. The installation is no longer in service as a presidential shelter, and is now used by the Federal Aviation Administration. The FAA has altered the exterior (and, presumably, the interior) of the facility for its purposes. These alterations include the addition of a self-supporting steel lattice tower supporting a large high-frequency (shortwave) rotatable log-periodic antenna for backup radio communications. The FAA's most recent construction project included adding and replacing several surface structures, and converting the grass helicopter landing zone into an asphalt-paved parking lot.
The FAA compound is a restricted area and is protected by security personnel and systems. Visitors are not admitted unless on official business.
For at least some its operational life, the PEF shared the mountaintop with two unrelated facilities: an AT&T microwave relay station and a fire-lookout tower. The AT&T facility was made obsolete by fiber-optic cables and has been demolished. The fire tower was converted to a radio tower serving multiple Maryland state and local government agencies. That tower, which was in very poor condition, has been replaced by a modern tower and building performing the same function.
This annotated image shows the installations on Lambs Knoll as of August 2006.