This crumbling UFO is one of only a few remaining "moveable ski chalets" of its kind.

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

A long-forgotten Victorian swimming hole is still a fun spot for a dip.

Not one, but two of Frank Lloyd Wright's architectural masterpieces nestled on the same street.

At this 1940s-era neighborhood favorite, you can still drink a cherry phosphate.

The main gates have been locked since 1745 and will remain so until the Stuart Dynasty returns to the throne.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

This site was once the largest ski jump tower in the world.

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

The "Rocky Horror Picture Show" character has a hidden camera that broadcasts people doing the "Time Warp."

This abandoned iron furnace was one of the first to use coke—a type of high-carbon fuel—to make iron.

On October 26, 1963, a 12-kiloton nuclear device was detonated here in granite some 1,211 feet below the ground surface.

Train fans from all over flock to this railroad viewing park where three lines converge.

This Roman underground canal was the longest tunnel ever built until the late 19th-century.

An abandoned observatory in the middle of the Illinois prairie.

When the town wouldn't allow the fast-food behemoth to build a new restaurant, they put one inside an 1850 home.

This twice-relocated "Usonian" home is among the smallest built by master architect Frank Lloyd Wright.

This museum is filled with an eclectic collection of unique inventions.

This abandoned bridge to nowhere stands secluded in the woods of a Cleveland suburb.

An abandoned suspension bridge on the Falkland Islands is crumbling into the water.

The first ever diner included on the National Register of Historic Places is famous for its custard French toast.

An abandoned skate park located in the middle of the wilderness.

Explore the dark underground corridors of this graffiti-covered former military fortification.

All that's left of the quintessential "cabin in the woods."