This is not your typical jungle gym.

Less a museum than a bizarre fantasy world created by artists and engineers.

Beside some power panels, a plaque celebrates the history of an alternate world.

Tour the sci-fi-esque reality of governmental disease management.

Who needs fancy modern water slides when this giant North Carolina rock works just as well?

Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

Mile-long cave system near Great Smoky Mountains.

A hidden network of subterranean passageways lies tangled beneath Indianapolis' bustling City Market.

A medical facility that has been kept frozen in time.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

What is it about mushrooms that makes people wish they lived inside of them?

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

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

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

One person's lost luggage is another person's treasure.

An unknown Hall of Fame in Jackson, Tennessee.

Visit this playground of waterfalls, caves and sinkholes.

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

The United States's largest hand-dug well is topped with a state-of-the-art museum.

The Bucyrus-Erie model 1850B electric shovel, or "Big Brutus," the largest existing electric shovel in the world.

The first home of the doomed aviatrix Amelia Earhart.

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.

Home to Hollywood history and a very special salt crystal.