The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A museum dedicated to the history and exploration of both popular music and science fiction.

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

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

A Saint Nicholas-themed ghost town in the Mojave desert.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

An urban laboratory.

This Tang Dynasty behemoth is the biggest Buddha in the world.

San Francisco Bay's ghost town.

Statue of Lenin, from Cold War era Czechoslovakia, now in a neighborhood of Seattle.