A mysterious "wedding cake" castle in the middle of the urban desert.

The unusual burial monument of Arizona's first governor.

These free-roaming horses were once destined to disappear from the land.

This 40-room dwelling tucked within a cliff was built by the basin's prehistoric residents.

An ambitious developer built what was once the world's tallest fountain in a Phoenix suburb.

Nothing to see here.

Opinions differ as to whether this Arizona tree was actually used as a Wild West jail, but that hasn't stopped the town from capitalizing on it.

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

These elusive, isolated rodents evolved into a distinct, locally iconic subspecies.

Every year, festive decorations appear on this juniper tree located in the median strip of a busy highway.

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

An urban laboratory.

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

A once popular resort—said to be the vacation spot of gangster Al Capone—now remains abandoned in the woods of Arizona.

The cinder cone volcano with a less than complimentary name.

This sinkhole in the Arizona desert is filled with carbonated, arsenic-rich water

This 24-acre park offers a place for meditation in the midst of Sedona's iconic red rocks.

The world's only teal arches exist in a city that cares more about its aesthetic than an Instagram influencer.

A spiritual vortex among the red rocks in Sedona.

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

A mysterious spirit totem at the edge of Navajo lands.

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

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

The final resting place of the businessman-turned-astronomer who helped discover Pluto stands near his observatory.