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

When ecosystems collide in the arid Southwest.

These aggressively sustainable art homes look like something out of 1970's science fiction.

A multi-storied adobe complex has been inhabited for more than a thousand years.

This museum started as a collection of Manhattan Projects and continues to add exhibits as they are declassified.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

This southwest-styled home in Santa Fe claims to be the oldest house in America thanks to an ancient bit of foundation.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

This sandstone mansion was the home of two of Oregon's most important pioneers.

Portlandia is the second-largest copper repoussé statue in the United States.

The remains of the first saint from Alaska in the Russian Orthodox Church.

Buy your friend a drink or staple some cash to the wall for the next guy at the Salty Dawg Saloon.

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

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

This WWII-era military installation once held an entire city within its walls - now, its walls are falling down.

At 238 feet above the bottom of a gorge this span is known as the biggest thrill on the road to McCarthy.

An Alaska livestock farm devotes itself to harvesting wool from creatures that once ran with mammoths and sabertooth tigers.

A trading post in the North Pole where children send letters.

North America's first frozen mummified remains of an ice age steppe bison, the 36,000 year-old mummy named "Blue Babe."

Four-story concrete hotel never opened to customers.

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

This ceremonial mound is one of the first officially recognized Native American historical sites in North Carolina.