An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.

The randomness of this wall of lava lamps helps encrypt up to 10 percent of the internet.

Eons old volcanic activity created one of the most stunning rock formations in the United States.

This small-town Connecticut restaurant gives each diner a free book from its vast library.

A house carved into a rock in the 1940s.

Historic funicular railway, believed to be the shortest railroad in the world.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

The superstar of Cold War nuclear bunkers has been featured in countless films but is now barely operational.

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.

An essential stop before plundering, BYO Cutlass.

Less a museum than a bizarre fantasy world created by artists and engineers.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

The highest bridge in America was built for an almost unnervingly small amount of money.

This charmingly homemade amusement park has been growing for 40 years.

A bizarre roadside attraction and the first instance of miniature golf in the world.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Rare recess caves fill this unbelievably beautiful Ohio park.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

This serene oasis in an affluent Los Angeles neighborhood holds some of Gandhi's ashes and got Elvis into Eastern Philosophy.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

Private collection of art inspired by cabinets of curiosity.

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.