The world's longest known cave system.

This modern castle sat empty for decades before a fire inspired its builders to complete its luxury halls.

A local scoured more than 1,000 acres for stone to create his masterpiece.

Unique tower has outlasted a takeover of the company.

An oversized metal construction of Billy Tripp's moods going through life.

Crumbling Kennedys and a decaying Tecumseh are just some of the haunting remains of one man's cement art trail.

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

Outsider art meets paleontology at this roadside reptile repository.

Niagara Falls holds a special place in Nikola Tesla's history, so they put a statue on it.

This lone tree and dramatic sandstone outcropping are so beloved by Michiganders they can be found on one of the state’s coins.

The only known Futuro house in North Carolina sits along a stretch of desolate highway on the Outer Banks.  .

Burial site more than 300 years old.

Originally a brothel during the Klondike Gold Rush, this bar once used dolls to denote when ladies were working.

The facade of this relic from the Klondike gold rush is decorated with over 8,800 pieces of driftwood.

I Street Bridge is the heaviest swinging center bridge in the United States.

Millions of years of oxidation make a drive down this winding Death Valley road surprisingly colorful.

"Only the devil could play golf here."

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

The longest continuous underwater road in North America was built at the insistence of Franklin Roosevelt.

The largest guitar store in the world has been visited by some of music's all-time greats passing through upstate New York.

A former poultry store that looks like a giant duck and is one of the "seven wonders" of Long Island.

A beautiful final resting place with some surprising residents.

The floor-to-ceiling collection in an old factory is a unique alternative to stuffy galleries.

A large camera obscura, constructed entirely from digitally fabricated components.