The lobby of this hotel near the U.S.-Mexico border features a stained-glass mural that measures 42 feet long and 6 feet tall.

A planet-hunting astrograph built in the 1920s to seek out the so-called "Planet X" beyond Uranus.

An excursion train traverses a picturesque red-rock canyon along the Verde River.

Crafted in 1911, this steam locomotive spent its entire working life in Flagstaff.

Red sandstone structures dominate this landscape, which has been inhabited for some 5,000 years.

This Native American settlement dates back to the Pueblo II period.

The first steel dam in the world and the only one still functional in the United States.

A strenuous, unofficial trail leads to spectacular views in one of America's most remote national monuments.

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

One of the largest open-pit copper mining operations in the entire country.

This huge dam across the Colorado River caused an armed standoff between two U.S. states.

One of the most extensive and well-preserved collections of dinosaur footprints in North America.

One of the final grand railway depot hotel complexes is slowly being restored to its former glory.

This ancient trail has claimed the lives of over 2,000 people.

The largest copper mine in Arizona, this enormous open pit emerges from the hills like an alien landscape.

This oasis-like spring in the Sonoran Desert is home to unique, endangered species.

This remote desert watering hole has a connection to a curious chapter of American history.

An incredible airplane graveyard sits outside this small museum dedicated to preserving aviation history.

Rusting dinosaurs frolic at the entrance to this roadside "snake sanctuary."

This Old West prison built into the side of a cliff was said to be inescapable.

An off-the-beaten path cave with an underground lake.

The biggest solar telescope in the world helps reveal the secrets of our sun.

The shop's owner has spent decades in the desert wearing nothing but a strategically placed sock.

The cinder cone volcano with a less than complimentary name.