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

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

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

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

The eccentric mansion of one of the most popular horror authors of modern times.

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

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

The longest navigable underground river in the United States is home to countless blind and albino animals.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

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

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

Rare recess caves fill this unbelievably beautiful Ohio park.

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

Private collection of art inspired by cabinets of curiosity.

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

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

A little piece of the Shire is hidden behind a plant nursery in Port Orchard, Washington.

A meditative space out of a fantasy story.

A mysterious monument meant to be a guide into "an Age of Reason" was destroyed after an apparent bombing.

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

Collapsing castle on the Hudson river was once the storage site of military surplus business.

A house filled to the brim with oddities and curiosities.

This Los Angeles animation studio is keeping the wonder of stop motion puppetry alive.

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