Italian cave with exceptional acoustics and an unsavory history.

The world's most active stratovolcano is almost always erupting.

This Stone Age solar temple aligns with the sun on each equinox and solstice.

Every inch of this chapel is covered in craftsmanship from across the world.

"We Seceded Where Others Failed."

A monument celebrating the idea of reaching inaccessible places.

Island ghost town detailing Flagler's folly in building the Overseas Railroad.

The inspiration for the Patagonia Clothing logo, Cerro Fitz Roy turns pink at sunrise.

Oldest building in California still in use.

The final resting place of 121 victims of the RMS Titanic, 42 of which may never be identified.

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

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

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 and an abandoned gold mine and ghost town all in one place!

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.