The Dover International Speedway is home to a towering, concrete-skinned, racecar-hungry behemoth.

Hikers can still stroll beneath the long conveyer of this abandoned mining facility hidden in a West Virginia river gorge.

This abandoned dream castle and its cemetery look out over the city that once inspired their creation.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

The world's largest fire hydrant is supposedly tornado-proof.

This psychedelic tromp l'oeil seems to be beckoning drivers to crash into a wall.

According to local lore, this narrow passageway through two large rocks was accidentally created by the devil himself.

The highest point in South Dakota contains the ashes of Valentine McGillycuudy, the "Holy White Man."

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

The world-record holder for the longest bridge stretching continuously over water.

This unusually circular centenarian barn became a Route 66 icon.

The future of roadside attractions is this sci-fi soda mecca that is home to a 66-foot tall neon pop bottle.

Nature's biggest mammal swims in landlocked Oklahoma.

An acoustic anomaly with a mysterious cause.

This massive boulder is inscribed with the story of a sensational hostage negotiation dating back to Colonial times.

It was an experiment to prove that glacial boulders and rocks can be used in constructions and dwelling.

This railroad tunnel was once the longest in Massachusetts.

Inspiring Herman Melville and Henry David Thoreau, Mount Greylock in western Massachusetts is the highest point in the state at 3,491 feet above sea level.

On top of Gibbet Hill lie the ruins of a lavish turn-of-the-century estate that never quite came to be.

This miniature feudal castle was built on a whim to honor a US Navy pioneer.

The ruins of a Massachusetts prison farm can still be found crumbling the woods of a state park.

One of the most scenic falls in Massachusetts has a history of death and grim legend.

This shifting North Carolina sand dune is an odd little desert surrounded by oceanic forest life.