The hidden lair of an alchemist rediscovered in a 2002 flood.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

An underground city of salt.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

Ride the subways of yesteryear.

Rent out a glass igloo to watch the Northern Lights like you live in the future.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

Hidden in an Italian forest is a completely homemade amusement park that has taken a lifetime to create.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

This historical theme park celebrates all things noodle.

A clear blue swimming hole with hidden caves, still unexplored.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Rustic natural hot springs in the deciduous rain forest.

This spa theme park lets its guests take a dip in pools of coffee, wine, or ramen broth.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A fifth-century temple improbably built into the side of a cliff.

A reproduction of earth's many biomes.

Take a drunken tour inside the world's largest known geode.

The longest hedge maze in the world.

The magic's in the hole!

A slice of central Asia in the middle of Berlin.