Rippling sand dunes frozen in the Arizona rock.

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.

A crumbling hospital from the 1850s on Roosevelt Island.

Thousands of small machines line the shelves of this personal collection which definitely delivers on its name.

This historic motel standing at the "crossroads of America" offers a radio in every room and was saved by local protesters.

An abandoned concrete jungle surrounded by a lush park.

In the St. Francois Mountains in the Ozarks at 1,772 feet above sea level, Taum Sauk Mountain is the highest (and possibly oldest) peak in Missouri.

A geological oddity formed by two rivers carving out a mass of limestone on both sides.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

A historic house in St. Louis was plagued by a series of suicides committed by family members involved in a successful brewery.

Erosion and time have created a naturally-formed water park.

Community bookshelf of 25-foot-tall book spines.

Curious cave that stays a cool 56 degrees all year long.

The world's largest man-made underground caverns offer unparalleled underwater wonders.

This abandoned prison castle has become an imposing gallery of graffiti art.

European castle ruins in an American state park are actually the product of death and grief.

This geodesic gallery holds a collection of painted spheres that make traditional canvases look lazy by comparison.

This replica stave church looks like a piece of Norway was simply plopped down in South Dakota.

The Largest Little Museum in the Northwest.

A memorial to a larger-than-life legend, inside a county that also holds Bunyan's death certificate.

One of the coolest murals in Minneapolis.

A mapping error in the 19th century made loggers think this section of the forest was underwater.

Secret hideaway for an alternative beach experience.

This bright yellow building is packed with sweet treats from all around the world, from chocolate-covered crickets to whoopie pies.