This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

This WWII-era military installation once held an entire city within its walls - now, its walls are falling down.

A humble air museum located in an original World War II aircraft factory.

The only retired U.S. nuclear missile silo that is open to the public.

This former Cyprus flight hub is now a crumbling, abandoned ghost complex.

This no man's land slicing through the island is strewn with abandoned relics of another time.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

At 207 feet, one of the world's longest continuous escalators.

Remains of the artificial harbours invented for the Allied invasion of Normandy can still be seen at sea.

A daring D-Day assault by U.S. Army Rangers is commemorated atop the high cliffs of this strategic point.

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

This too-low North Carolina railroad trestle is still a notorious big rig executioner.

The world’s largest combined collection of U.S. and Russian aircraft got its start in a poultry building.

An officers prison camp believed to be impregnable by the Germans saw over 30 successful escapes.

This sky-high radio mast is formerly the tallest man-made structure in the world.

A monument to the center of the North American continent may be off by a few miles.

These former Cold War launch sites have been preserved for tourists to see where the button might have been pushed.

Once America's longest-manned military fort, now an abandoned hulk.

A semi-scholarly approach to sex.

A legal loophole makes it possible to get away with murder within this 50-square-mile section of Yellowstone.

Naked scientists race around the pole in the frigid cold to try to join Antarctica's exclusive 300 Club.

Part of a secret 1970s nuclear defense program is now open to the public.

Model Trains and Much More in Hamburg.