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

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

A house carved into a rock in the 1940s.

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

Oh, just a motel on the edge of the desert decorated with thousands of clowns conveniently located next to an abandoned graveyard.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

This "zoo" is a cross between a junkyard and a sculpture garden, featuring animals you won't see anywhere else.

Canyon walls shrouded in ferns.

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A common entry point to the Griffith Observatory trail holds its own wonders.

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

Tucked in a nondescript downtown Brooklyn mall is a bar containing a remarkable turn of the century anatomical wax collection last seen in 1920s Berlin.

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.

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

An abandoned stretch of highway, deteriorating next to the operational one.

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

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

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

Hidden beneath a bridge, this waterfall is known for the large amounts of graffiti painted on its base.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

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