A volcanic tunnel illuminated by natural skylights offers a shaded respite from the desert sun.

Eons old volcanic activity created one of the most stunning rock formations in the United States.

The unusual patterns in this rock formation result from two distinct modes of weathering.

A tunnel with windows, so you don't miss out on the impressive views.

The ghostly remains of what was once the world's richest copper mine.

The world's longest known cave system.

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.

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."

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

These ruins of a pre-Columbian cliff village are among the most beautiful and well preserved in New Mexico.

The illuminated falls are a gem in North Cascades National Park.

A museum in rural Utah documents the history of the Japanese Americans who were forcibly relocated there.

A cozy bookstore is tucked within an old gold mine shaft beneath the cafe and ice cream shop.

This Native American settlement dates back to the Pueblo II period.

The Jewish section of the famous Boothill Graveyard was abandoned for nearly 100 years.

This quiet chapel was central to a community of settlers who reclaimed an abandoned fort.

This reclusive Hopi village in Arizona has been continuously populated longer than anywhere else in America.

More than 300 years ago, a revolt at this Hopi pueblo shaped the future of the American Southwest.

Legend says train robbers stashed their gold within the depths of this unusual cave.

A partial tunnel blasted into a steep ridge is all that remains of a failed railway across Arizona.

Once the product of an inexplicable gold strike, this ghost town is now home to one man and his love of classic machines.

This 40-room dwelling tucked within a cliff was built by the basin's prehistoric residents.