The centuries-old trees lining both sides of this dirt road may become Madagascar's first natural monument.

This ancient subterranean megalopolis is known for the hot oil traps that were installed above each of its entrances.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

One of the largest caverns in the world has a maw large enough to stack cathedrals in.

This short bridge is the only thing connecting a tiny Irish island to the mainland.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

This historic iron-working village is now a ghost town so immaculate that it looks as though it was recently built.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

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

These picturesque Hawaiian falls are home to a rare species of fish that uses a special sucker to climb up cliffs.

This tiny New Jersey village has lived many lives but seems determined to remain a ghost town.

The highest bridge in America was built for an almost unnervingly small amount of money.

This modern monument to pagan belief looks like it was transported straight from ancient times.

This small group of sand dunes manages to pack in a strange rainbow of colors.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

Elephant seals and sea lions have turned the abandoned buildings on this island into their endangered love shack.

Isolated atop this Balinese sea crag is a lovely Hindu temple that is said to be guarded by sea snakes.

This scenic gorge is named after one of the most famous Bigfoot attacks in pseudohistory.

This foolish Victorian sea fort was converted to a deluxe hotel.

This giant boulder is pinched over a 1000-meter abyss by two mountains.