World's first "penitentiary," meant to be humane, drove men insane.

Rippling sand dunes frozen in the Arizona rock.

An exquisite tunnel of cascading flowers.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A terrific purveyor of natural history objects and curios.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A huge musical instrument played by the ocean.

On Japan's Tashirojima Island, cats are king.

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

A domed disco abandoned since the '70s now attracts artists and explorers under its unique roof.

An eerie, derelict amusement park in Berlin.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

Submerged busts of communist and socialist figures from the USSR.

Space-age monument to an early 20th-century uprising.

A highly symbolic tower in honor of Supreme Leader Kim Il-sung's personal philosophy.

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

Dr. Strangelove-esque tours reveal the inside a bunker once reserved for Stalin himself.

A nuclear power plant abandoned along with an international allegience.

This brutalist monument is inscribed with 9921 names of Yugoslav partisans who perished during WWII.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

An Italian hillside ghost town.

As the aging humans of this Japanese village die off one local artisan is replacing them with eerie homonculi.