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

A hollow cement depiction of time's inexorable effect on the human body.

Historians and hobbyists head to this former French outpost for the annual Feast of the Hunters' Moon.

The first spinning jail built in the United States is the only one that still turns.

An opulent testament to the boom-and-bust history of industry in north central Indiana.

This large, castle-like structure is hidden amid the mountains on the grounds of the Utah State Hospital.

The remains of this early 20th century refinery loom on a mountainside like a graffiti-covered fortress.

An absolutely beautiful 200-foot stained glass installation traces the evolution of knowledge.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

A subterranean world of tunnels links several buildings of this rare 19th-century asylum.

The last SR-71 ever constructed.

This granite monument at the site of an ill-conceived tourist attraction is built from the same stone as the Mormon Temple.

Hidden on the 7th floor of a historic building, this Cajun spot features wall-to-wall bottles of hot sauce.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

At the tallest peak in Colorado, an electrifying mix of thin air, lightning, and rivalry.

Once an unstoppable source of gold and silver, this town came to a grinding stop when the groundwater proved deadly.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

Even in death, he's still your huckleberry.

The site where a nuclear bomb was lowered over 8,000 feet underground and detonated as an experiment in natural gas extraction.

It would be easy to walk past this unusual piece of art and have no idea it pays tribute to the odd life of a real chicken.

A ghost town that held steady longer than most, but finally gave up the ghost.

A self-built castle made by a mysterious man.

Search for traces of the dinosaurs that roamed here more than 90 million years ago.