Camp Peary was opened in 1942 as a Seabee training facility, but has since been vacated and reclaimed as a Navy facility. It is also home to “The Farm,” a CIA clandestine officer training facility.

Seabees demolition practice, Camp Peary, Virginia.

Smack dab in the middle of the New York Metropolitan Area, and right next to Riker’s Island, North Brother Island is a small and uninhabited mess. Now officially a bird sanctuary, it used to house the Riverside Hospital for quarantinable diseases, and was bought back by the government in 2007. Nobody is allowed entry without a permit.

The remains of Riverside Hospital on North Brother Island, 2006.

Bodies from the General Slocum shipwreck wash ashore on North Brother Island, 1904.

Mount Weather is the center of operations for Fema, and houses the FEMA National Radio System, and allows the president to access the Emergency Alert System. It is also a relocation site for high ranking officials in the case of a catastrophic natural or nuclear disaster. Its location was unknown until TWA Flight 514 crashed into Mount Weather in 1974.

"Crystal East Microwave Tower & Complex" Mount Weather VA.

While the Fort Knox army installation is well known, good luck getting in. Fort Knox houses the United States’ gold reserves, the exact worth of which is a closely guarded secret. It is still heavily guarded.

The Cheyenne Mountain Complex is a United States Space Force installation and defensive bunker in El Paso County, Colorado. The mountain was excavated for a command center during the height of the Cold War in the 1950s, and it now houses the advanced North American Aerospace Defense Command, (NORAD).

This 25-ton North blast door is the main entrance to another blast door, beyond which the side tunnel branches into access tunnels to the main chambers.

The Harvey Point Defense Testing Activity facility is owned by the Department of Defense, and performs specialty military air operations. It has multiple landing fields, and airspace all around the area is restricted. It is also used for paramilitary and counterterrorism courses, and Seal Team Six reportedly trained for their mission on a full scale mockup there. People also claim to occasionally hear explosions coming from the facility.

Raven Rock Mountain Complex is part of the core bunker complexes, and has been called an "underground Pentagon.”

Plum Island is an island off the end of Long Island, which houses the Plum Island Animal Disease Center, responsible for researching potentially dangerous animal-born pathogens.