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

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.

Singing sand that stands as the final remains of an ancient lake.

Only intact Ichthyosaur skeleton in the United States.

Towering basalt columns, a creation of fire and ice.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

An extensive collection of ancient Egyptian artifacts and mummies.

Home to the deepest rift anywhere on Earth.

Bits and pieces from the ill-fated Donner Party's winter cabins.

Men in rubber-soled boots serve as your "brakes" on this toboggan ride Hemingway described as "exhilarating."

The Empire Mine is "one of the oldest, largest, deepest, longest and richest gold mines in California."

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

This massive redwood tree has a hole in the base big enough to drive through.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Medicinal spa created with the discharge from a geothermal energy plant.

Giant topiary dog once played a role in a terrorist bomb plot.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

Abandoned 18th century weapons factory in the Aezkoa Valley.

Bordered by forest on three sides and the ocean on the other, the Great Dune of Pilat is the highest sand dune in Europe.

The largest underground church in Europe.

The world's largest solar furnace uses 10,000 mirrors to concentrate the sun's rays to generate power.