The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

Look closely and you’ll notice that the color changes a third of the way up the tower.

The "lovely red Vega" of the legendary record-settling pilot.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

There’s a hidden military meme engraved on the World War II Memorial.

A celebration of capitalism in Midtown.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

At 207 feet, one of the world's longest continuous escalators.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

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

Georges Seurat’s pointillist masterpiece has been recreated in Ohio in topiary form.

This replica of the Greek structure is in the heart of Nashville.

Known as one of America's most beautiful public restrooms.

Every day a troupe of pampered water fowl walk the red carpet to their favorite fountain.

Walk the whole Mississippi River!

The hotel where Martin Luther King Jr. was shot is now a museum dedicated to his work.

Hundreds of protractors affixed to surfaces all over the city.

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

Color-coded signs direct drivers on a network of routes designed to avoid Pittsburgh traffic.

This spot memorializes one of the greatest plays in NFL history, unless you happen to be a Raiders fan.

Fears of Satanic worshippers swirl around five Celtic-inspired megaliths.

The "world’s largest honky-tonk" also has its own indoor rodeo arena.