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.

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

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

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

A small side chapel in Santa Fe's basilica is home to the oldest statute of the Virgin Mary in North America.

The oldest continuously occupied public building in the United States.

A natural formation that resembles a camel resting in the New Mexico desert.

Home of the International Space Hall of Fame.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

This is one really big nut.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

This roadside attraction has been serving out its fair share of hearty folklore and chaos since 1858.

Andy Griffith's hometown has made itself up to look like the fictional town of Mayberry.

A six-foot pair of socks hangs from a drawer of the world's largest bureau.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

Jule Körner's house full of bizarre architectural details.

The oldest continually operating golf course in the United States.

The last remnants of Fort Pitt also hold the distinction of being the oldest structure west of the Allegheny Mountains.

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

This extraordinary Depression-era expenditure was modeled after a postcard of a Mediterranean hotel.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

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