Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

Legend says that this short Canadian tunnel still holds the dying screams of a girl who burned alive.

The haunted reputation of these abandoned Colorado train tunnels is probably not helped by the terrifying spiked fence.

The atomic museum in the basement of this German castle displays long strands of replica uranium cubes.

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

For just a few bucks, this Iowa funicular will let you feel like an 1800s fat cat.

This sprawling Belgian fort was once thought of as impenetrable but now it is simply an abandoned relic.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

This iron and wood Civil War city-ship was the first vessel to be sunk by an electrically detonated torpedo.

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

This abandoned Civil War fortress is slowly being swallowed by the waters of Lake Borgne.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

Pirates had to be ousted from the land where this now ruined Louisiana fortress was built.

The crumbling ruins of this southern American fort have survived storms, war, and cults.

This abandoned sea fort has become an accidental bird sanctuary.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

One of the only Florida forts to remain in the hands of the Union all through the Civil War still stands as a historic stronghold.

A quartet of rusting satellite goliaths are all that remain of a communication network that protected Britain from German and Russian air strikes.

This Cold War siren is one off the last of its kind still standing with its immensely powerful original horn.

This top-secret nuclear bunker hidden in a Bosnian mountain has been converted to a modern art exhibition space.

This East German military command bunker was ready for World War III.

Canada's subterranean Cold War museum has doubled as a movie set.

Concrete crosses scattered across the Arizona scrubland which were used to align spy satellites.

Why have you never heard of the second most popular tourist site in New York?