This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

Giant origami sculptures tucked into desert scenery beckon passers-by to explore further.

Deadly airliner crash preserved for those willing to climb and pay respects.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

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.

Rippling sand dunes frozen in the Arizona rock.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

America's only nuclear missile silo open to the public.

The world's largest military aircraft cemetery.

An Arizona museum with a collection of pharmaceutical oddities, including a jar of a gangster's chewed gum.

See massive fossils that are over 200 million years old in northeastern Arizona.

The wreckage of a deadly bomber plane crash can still be found near an Arizona peak.

The largest natural travertine bridge in the world is nestled in a small canyon in central Arizona.

Every Christmas, one Arizona city makes the most of its dry climate by creating an arid desert tannenbaum.

Thousands of Mexican Free-Tailed Bats soar around an abandoned storm drain at sunset each summer.

A cave's rare beauty held a cavernous secret hidden underground.

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

A beautiful but toxic fountain of mercury.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.