Australian Lake set aglow by Noctiluca Scintillans.

Dilapidated ruins that once treated a notorious young serial killer, currently hosting vandals, squatters, and ghost hunters.

In a long-dry lake bed, these groups of massive stone pillars bear a striking resemblance to clumps of everyone's favorite fungi.

An abandoned saucer-shaped monument in the Bulgarian mountains.

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

Moss and stone turn this waterfall into an otherworldly liquid veil.

Hiding the longest subterranean river known in the world.

Ancient man-made caves underneath small town Belgium.

Louise Bourgeois' 30-foot-tall steel spider sculpture.

A hands-off space for graffiti artists to hone and display their skills.

The largest of London's subterranean rivers and once a mad, bad center of London life.

A mysterious artist-run cabinet of curiosities and library.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

Constantly maintained, this organ is playing a six-century long composition by John Cage.

Living trees form the structure of an open-air palace.

Hot springs monkey spa in the middle of Hell's Valley.

The ruins of Japan’s premier water brothel.

Bioluminescent firefly squid light up this Japanese fishing port.

A failed Russian themed village and amusement park in Niigata prefecture.

The ruin of a Japanese love hotel almost completely overgrown with brambles.

This ruined Japanese stripclub sits half burnt to the ground.

A beautiful, dense forest in the shadow of Mount Fuji, with a tragic reputation.

The world's largest drain sits below the city of Kasukabe, Japan.

This seven story Japanese love hotel now stands in ruins.