An abandoned network of military bunkers and tunnels open for anyone willing to descend into the darkness.

See massive fossils that are over 200 million years old in northeastern Arizona.

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

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

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

The 7,000-year-old calcium carbonate formation creates a magnificent natural bridge.

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

The official atomic museum of the United States explores the explosive and productive history of a much maligned energy source.

Thousands of pieces of art have been carved into the rock at the site of an ancient volcanic eruption.

You were once able to challenge a chicken to tic-tac-toe at this park, which is now converted into the Aikman Wildlife Adventure.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

The last location where Buddy Holly, Ritchie Valens, and J. P. "The Big Bopper" Richardson played before their tragic deaths.

The final resting place of the most famous outlaw in the Old West.

A museum dedicated to the alleged Roswell Incident.

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

A monument celebrating the idea of reaching inaccessible places.

This red-eyed chrome beast pays homage to the popular modern myth of West Virginia's insectoid monster.

A small storefront museum explores the history and myth of West Virginia's famous urban legend.

A giant pair of thick black glasses mark the tragic demise of a trio of rock and roll legends.

Launchpad for the US military’s dead mouse operation to battle millions of snakes.

Kuwait City's uniquely designed water towers look straight out of a retro sci-fi cityscape.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

A rare chance to get up close and personal with a 13-mile ribbon of ice near downtown Juneau.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.