These ancient sunken lanes were naturally tunneled into the soft ground by countless footsteps.

Teeming with illegal goods and services, this towering maze of vice is also a popular tourist accommodation.

The world's longest outdoor covered escalator system transports commuters through Hong Kong's hilly terrain.

On the Pakistan-India border the militaries perform an elaborate theater of aggression each and every night.

These eclectic homes nestled into the cliffs of a Caribbean island were built entirely from scavenged materials.

Museum dedicated to awful artwork.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

Cryptic messages embedded in the New York City sidewalk.

The first spinning jail built in the United States is the only one that still turns.

The longest living non-clonal organisms on Earth.

The remains of diamond fever taken over by the desert.

This "dead marsh" sits among the largest sand dunes in the world, a forest frozen in time.

Tubing through a cave lit with glowworms is a magical underground experience.

Morocco's Argania trees are infested with nut-hungry goats.

The massive cave church of Cairo's Zabbaleen community is one of the largest Christian churches in the Middle East.

This family tattoo parlor has been inking religious pilgrims in the Middle East for 700 years.

A Hawaiian stairway to heaven—that you can't climb.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

An eerie, derelict amusement park in Berlin.

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

This bike path was sunk below water level for maximum wonder.

The best-preserved ancient theater in the world.

This neon blue river gets its color from a unique mix of bacteria and volcano minerals.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.