A self-built castle made by a mysterious man.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

Rippling sand dunes frozen in the Arizona rock.

Most-visited and most-photographed slot canyon in the American Southwest.

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

In the middle of the Alaskan wilderness, lies a train trestle to nowhere.

Tour a Cold War-era U.S. military missile launch site in Anchorage.

The crumbling remains of Juneau's explosives storage site.

A hulking remnant of Alaska's industrial gold mining boom in the 1920s.

A 30-mile-long glacially-carved canyon leads to a massive pair of glaciers.

Considered by many to be one of the most dangerous highways in Alaska.

Open day and night, a church with three pews and Bibles.

This abandoned mine offers a glimpse at what life was like for those who came to Alaska seeking Gold Rush riches.

Every summer, the Mendenhall River greenbelt comes alive with an explosion of magenta flowers.

This remote fort on the Yukon River is a vestige of the wild Alaska gold rush.

A suburban street in Anchorage doubles as a runway, and each home has its own airplane hangar.

Alaska Natives have lived on this tiny isolated island in the Bering Strait for over 5,000 years.

An auroral research program that superheats the ionosphere.

The ruins of a town wiped out by the second-largest earthquake in recorded history.

Colorful boxes placed over the dead are left to rot and crumble.

Four-story concrete hotel never opened to customers.

This ghostly Alaska village still clings to a steep cliffside despite having been abandoned for over 50 years.

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