The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

A beautiful geyser under environmental threat.

The first declared National Monument in the United States.

At one time this small mining village was the highest town in America but now it sits abandoned while the mine churns on.

The remnants of the base where US Army troops learned how to fight in extreme conditions.

All that remains of this once-booming mining town are the ruins of a saloon.

Once a lonely sentinel on the edge of the Great Plains, this rebuilt trading fort offers a glimpse of life on the Santa Fe Trail.

The remains of a World War II-era Japanese American internment camp dot a windswept Colorado hill.

The scene of one of the darkest moments in American labor history has been left essentially untouched since the tragedy.

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

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

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

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

This grand stone tower was dedicated to a famed American humorist almost by coincidence.

This Boeing KC-97 tanker is now a restaurant for aviation lovers.

The largest self-built castle in the U.S., six decades in the making.

This three-mile concrete levee in Pueblo, Colorado was transformed into the world’s longest painting.

This volcano rises like a giant anthill from the plains below, with a road spiraling up to the rim.

A somber monument commemorates the site of a Native American reservation marked by suffering.

Home of the International Space Hall of Fame.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

The final resting place of the living embodiment of the famous Forest Service symbol.

The site of Billy the Kid’s most famous escape and the end to the Lincoln County War.

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