What was once an underground Nazi city is now Europe's largest bat reserve.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

Legend says train robbers stashed their gold within the depths of this unusual cave.

Ancient pueblos built into the base of a natural canyon wall.

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

Most-visited and most-photographed slot canyon in the American Southwest.

A sharp bend in a dramatic river canyon cut through red rocks.

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

This abandoned horse racing track was an exercise in hubris from its inception.

A stone pillar marking the location of the westernmost battle of the American Civil War only honors one side of the conflict.

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

A Wild West jailhouse that slid down the mountainside.

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

The highest point in Arizona is an oddly snow-topped peak within the otherwise arid state.

Walk through the actual strap iron cells and solitary chambers of Arizona Territory’s first prison.

Once the product of an inexplicable gold strike, this ghost town is now home to one man and his love of classic machines.

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

This striking public art installation is suspended above a public park, designed to gently move in the breeze.

Limestone caves with spectacular showcase chambers.

On the outskirts of a reborn ghost town, a decaying post office remembers the bad old days.

Open since 1938, this diner has kept its fountain, malt machine, and all the gum that greasers left beneath its counter.

A geological mystery on Camelback Mountain.

Come for the pizza, stay for a performance on the world's largest theater pipe organ.