One of the Cemestos prefab homes built to secretly house thousands of Manhattan Project workers.

Crumbling ruins mark the site of a couple's grisly murder in the woods.

Enormous lake at the bottom of a unique cave system.

Famous for its bio-luminescent inhabitants, known as "dismalites."

Patrick Dougherty's fantastic living tree sculptures, mind-blowing but temporary.

The perfectly named cave drop is the deepest in the continental United States, almost matching the height of Seattle’s Space Needle.

The Trappist monk, prophet-poet, and rebel never really got to live out the eremitic life he was seeking.

You'll need cowboy boots to trek to this old-fashioned saloon nestled in a giant natural cave.

River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

A failed utopian experiment for British expats in the American South is now a Victorian village frozen in time.

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

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

This architectural triumph is the only Frank Lloyd Wright house in Alabama.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

The longest non-mortared wall in the country is one man's tribute to his displaced Yuchi ancestor's five-year journey to her homeland.

This structure among the trees was the result of divine inspiration.

A natural sandstone bridge hidden in the Sewanee forest.

An abandoned theme park with a strange and tumultuous past.

The world's longest known cave system.

A museum to a cave explorer whose tragic death was a media sensation, and whose corpse became a tourist attraction.

An ancient cave system in Tennessee’s Appalachian foothills converted to a 1,200-person music venue.

A former 19th-century tavern, famous for its peach brandy and honey concoction.

These early tent-shaped grave coverings are unique to Appalachia.

Eight rare Corvettes are swallowed up by a sinkhole in Kentucky's National Corvette Museum.