What is the Thing?

Limestone caves with spectacular showcase chambers.

An old saloon in the West filled with history, and according to some, a few dozen ghosts.

The unusual burial monument of Arizona's first governor.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.

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

Legends surround this jagged rock formation in the New Mexico desert.

The hallowed remains of a 900-year old Ancestral Pueblo great house.

The fifth-longest natural arch in the world, and the longest outside China.

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

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

One man has installed bathtubs into the Utah desert floor to harness the powers of a natural hot spring.

When it was built in 1929, this historic bridge was the only place to cross the Colorado River for 600 miles.

Dramatic river bend surrounds a natural red-rocked pedestal.

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

This quiet park's strange sedimentary spires were named after Kodak's color film.

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

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

The unusual patterns in this rock formation result from two distinct modes of weathering.

A tunnel with windows, so you don't miss out on the impressive views.

Narrow slot canyons in a badland eroded into soft sedimentary rock provide an otherworldly landscape in this remote Nevada state park.

The self-proclaimed gateway to the Extraterrestrial Highway.

This sign designates the road that leads to the infamous Area 51.

This Old West eatery along America's Loneliest Road was originally a stop on the Pony Express.