The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

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

This is one really big nut.

More than 21,000 images fill this overlooked gem of a prehistoric site.

The old Route 66 town straddling Texas and New Mexico died along with the Main Street of America.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.

Ute tour guides have been sharing the ancient dwellings and rock art inside this large park with visitors for more than 40 years.

Legends surround this jagged rock formation in the New Mexico desert.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

A dangerous narrow-gauge railroad once traced a route through this striking canyon.

For over a century, it has been a tradition to raise a flag at the top of this 450-foot sandstone pillar on the 4th of July.

This open-air reconstruction of an Old West town, a cross between a theme park and a museum, provides an immersive historical experience.

The largest source of fossilized insects anywhere.

While most of the games in this arcade take quarters, that would have been a small fortune when they were made.

Hidden beneath a bridge, this waterfall is known for the large amounts of graffiti painted on its base.

This enigmatic building features numerous architectural styles.

This super steep hike ascends 2,000 feet in less than a mile.

There are eight natural springs around town, each with a slightly different taste.

These faux-cliff dwellings allow visitors to climb around on a replica archaeological site.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

Victorian "Fancy Craft" Hair Wreaths and Relics.

The haunted reputation of these abandoned Colorado train tunnels is probably not helped by the terrifying spiked fence.

Thanks to a quirk of elevation this gift shop produces magic doughnuts that are found nowhere else on Earth.

The highest bridge in America was built for an almost unnervingly small amount of money.