The second largest in the world, this massive underground void has its own subway.

This Costa Rican topiary park is a surreal garden of unearthly delights.

The decaying remains of a once-luxurious Soviet spa town.

The cave holds a spectacular array of stalactites and stalagmites, including one shaped like a giant human heart.

This neon lit Georgian cave claims to hold the boulder Prometheus was chained to.

World's oldest and largest space launch facility, once a secret missile testing site.

Bizarre dirt trail winds a narrow path above the tree line.

During the rainy season, this temple is almost entirely submerged, accessible only by boat.

This museum has a most unusual location: inside a giant, three-headed elephant.

From dragonfruit to mangoes to durian this Thailand resort allows guests to stay inside all manner of giant fruit.

Derelict airplane bodies serve as both home and income for three Thai families.

A limestone wonderland of water and subterranean secrets.

Acres of salt crystal pyramids dry in the sun along Thailand's "salt road."

The Yonaguni Monument, a natural formation or the Japanese Atlantis?

It took 28 years to build this massive statue of the Hindu god Vishnu riding a mythical bird.

Complete town of 5,000 living out at sea on the world's first offshore oil platform.

Spring that emits water and fire at the same time is said to have remedial properties, and sparked its own religion.

Foreign invaders almost left this lovely Caucasus palace alone—almost.

What might be the largest completely Jewish town in the world outside of Israel now faces dwindling numbers and empty streets.

Relax on your veranda and watch the light show.

From prostitutes to soldiers to business men, the dead in this graveyard are a microcosm of Singapore's history with Japan.

A Singapore shrine to an unnamed German girl who has become a local deity.

This jam-packed Singapore antique museum preserves the fading remnants of a uniquely mixed culture.

This rare wildlife haven in Singapore feels like you're in the tropical rainforest.