The eroded core of an ancient volcano is now accessible by a short hike.

A partial tunnel blasted into a steep ridge is all that remains of a failed railway across Arizona.

A pair of giant roadside arrows are all that remains of a former Route 66 trading post.

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.

A nature and cultural preserve named for its multitude of petroglyphs carved by the Northern Sinagua people.

Arizona's first government hub is a rustic cabin now preserved as part of a historical museum.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

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

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

A Wild West jailhouse that slid down the mountainside.

An artificial crater field that trained astronauts for lunar exploration.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

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

The artist James Turrell is repurposing an extinct volcano crater as an observatory to experience the cosmos.

This historic national park is covered in the stunning ruins of red rock pueblos.