What is the Thing?

Limestone caves with spectacular showcase chambers.

A hand-built folk art installation covered with messages of God's love.

This abandoned Navy base was transformed into an off-grid alternative living community for thousands of people.

An off-grid art installation that encourages its visitors to imagine a world without waste.

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

Witnessing the might of this dessert-colored desert waterfall is a rare, powerful treat.

This memorial includes fragments from one of the greatest tragedies in United States history.

This public square capitalized on a single Eagles reference to bring some life back to an Arizona town.

This church on a Tohono O'Odham reservation has stood since 1797.

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

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

A reproduction of earth's many biomes.

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

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

This 1930s log cabin began as a taxidermy museum but is now a popular country music venue.

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.

A classic Route 66 landmark that was built with scrap lumber and is held together with kitsch and puns.

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

A spiritual vortex among the red rocks in Sedona.

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

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

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