Terraced flowerbeds and rock sculptures in the midst of the Minnesota wilderness.

The ruins of Theodore Roosevelt's beloved ranch stand in a forgotten corner of a national park named after him.

These cinderblock farmhouses were actually World War II radar stations in disguise.

The world's longest known cave system.

The simple log cabin of a famed loner and naturalist stands preserved as a symbol of the ultimate DIY lifestyle.

This conservation area is also home to many of the region's desert tortoises.

This historic hotel on Bathhouse Row in Hot Springs National Park has a storied history of gangsters and baseball greats.

Watch the newest land on the planet form before your eyes.

When ecosystems collide in the arid Southwest.

The only road through the heart of Glacier National Park.

The king of U.S. high points towers over every other peak on the continent.

Water of undetermined depth has attracted rare fish and cult leaders alike.

An abandoned Jazz Age dream home and con man's hideout in Death Valley.

The highest dunes in California are the most likely place in the area to hear the Singing Sands.

Ten 25-foot-tall, beehive-shaped kilns, abandoned in Death Valley.

Windswept and remote, this island was once the home of a rare mammoth and today is home to a rare tree.

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

Stroll through a wonderland of stupendous moss-covered trees.

Steep canyon walls hide a forested oasis in the West Texas desert.

When this test site was abandoned, they didn't even bother to take the rocket with them.

This angular Dwarven tunnel cuts through a mountainside in Glacier National Park.

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

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

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