The world's longest known cave system.

See the motorcycles that launched the stuntman to fame and the gear that saved his life.

This massive marble memorial was built bit by bit either out of devotion or spite, but at the expense of the surrounding town.

A unique gallery chronicles the losers of American presidential history.

Lone survivor from Custer's Last Stand forever preserved.

A museum documents the development of the invention that tamed the Wild West.

A museum where visitors can learn about greyhounds and (more importantly) pet them.

Small plaque marks the spot, but the true center is located about half a mile away on a private pig farm.

It's big, it's a ball, and it's made of twine—the world's largest of its kind.

One of the Eight Wonders of Kansas and the first official National Natural Monument these stark formations look like nature's Stonehenge.

A wonderful collection of all things Oz is nestled in the heart of Kansas.

An obelisk commemorating Lincoln's role in connecting the coasts.

The remains of a bustling turn-of-the-century park built to showcase the wonders of electricity.

An old town theater converted into a celebration of the hobo legacy.

A half-mile long and three stories high, this bridge over the Des Moines River Valley mimics a descent into a mine shaft.

The farm where one of America's greatest leaders was raised is now a well-appointed landmark.

A lesser-known part of the Kinsey Institute is this impressive collection of art, artifacts, and material culture related to human sexuality.

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

Once adorning a New York skyscraper, these reclaimed ruins now haunt an Indiana park.

Medical museum focused on antique anesthesiology equipment.

The palatial McDonald's that inspired Wesley Willis.

A Museum of Holography frozen in 1974.

A historic beacon built in the aftermath of the worst maritime disaster on the Great Lakes.

These abandoned grain silos and tunnels are an urban exploration dream.