The hidden offices underneath Memorial Bridge have been locked up since 1976.

In the basement of the U.S. Capitol Building is a hidden storage room full of ornate floor tiles leftover from the 1850s.

An 18-mile-long tunnel for sewage waste will soon wind within the bowels of Washington, D.C.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

Obscure Freemasons still live in D.C.’s largest private residence.

Despite many attempts to finish this overpass, it has been abandoned since the 1970s.

An abandoned stretch of elevated road in the middle of the Brazilian jungle.

Abandoned bridge hidden deep in the San Gabriel Mountains.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

An abandoned suspension bridge on the Falkland Islands is crumbling into the water.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

Nancy Thompson's Home from "A Nightmare on Elm Street."

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

A clerical error gave rise to this imaginary micronation in the southwestern corner of Estonia.

A California city claims to be the home of a fast-food classic.

A stone marker memorializes the spot where the King broke up a street fight with a classic karate stance.

The biggest and deepest Cold War bunker open to the public can be found in southeast England.

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

In the land of the Light Brigade stands a testament to the Cold War.

One of the most horrible legacies of the Cold War is a site where the Soviet Union tested nuclear bombs on civilians.

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

This Cold War–era underground city includes offices for Mao Zedong and Lin Biao.

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

This disused Cold War bunker has been restored to all of its early 60s glory.