A historic highway suspension bridge on the old Fraser River highway has been preserved for non-motorized traffic.

The last surviving footbridge in the Yakima Canyon, now a historic landmark, provides access to wilderness west of the Yakima River

An old copper mine in Plumas National Forest, formerly served by a tramway, seems to have been successfully remediated after years of acrimony and effort

An improbable creek near Death Valley, not far from the oldest surviving Euro-American structure in the Mojave Desert.

The only mine for rare earth elements in the United States has been intermittently active since the 1950s.

A whimsical display of massive metal sculptures made from recycled materials.

One of two observatories in the U.S. that routinely detect gravitational waves.

A large lava tube that can be walked through with no special equipment.

An extraordinary collection of aircraft and spacecraft on display at the original site of the Boeing Company.

At the site of the most dangerous crossings on the Oregon Trail, a museum explores the complex history of westward migration in America.

These massive concrete foundations and smelter chimney bricks still smell like smoke after a century.

One of Canada's premier radio observatories sits in a radio-quiet valley outside Penticton.

A construction mishap at this narrows on the Fraser River rendered it impassable to many migrating fish species, with international consequences.

The ruins of a failed dam that was built over land later described as a "sponge."

The morning of January 9, 1965, over 46 million cubic meters of earth, rock, and snow broke free, obliterating a section of the highway below.

On the side of Highway 50 East, between Carson City and Dayton, Nevada, sits a giant metal spider made from a vintage Volkswagen Beetle.

Nuclear reactor created the plutonium used on Nagasaki.

A 1940s nuclear reactor built to produce plutonium for the Manhattan Project.

The remote graves of a Scottish family who died of thirst while attempting to reach St. George.

Cross the Continental Divide through an old railroad tunnel, and ride back to the top on a shuttle.

This arid landscape was once a lush wetland. Today, it's a paleontological site filled with fossilized mammoths, sabertooth cats, and more.

Unopened beer cans are left at this monument to honor the Navy men who lost their lives during a training mission.

This silver-mining camp has been active intermittently from the 1860s to the present.

This incongruous small ferry across the Willamette River north of Salem, Oregon has been operating continuously since the 1850s.