An urban laboratory.

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

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

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

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

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

These petroglyphs created by ancient Arizonians have withstood centuries of exposure to the elements.

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

This small memorial is dedicated to the Perryville State Prison firefighters who perished fighting the Dude Fire in 1990.

A strenuous, unofficial trail leads to spectacular views in one of America's most remote national monuments.

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

Petroglyphs, bird watching, and a 100-year-old Ranch in one location.

Some 10,000 works of ancient rock art cover these volcanic basalt outcrops near the Gila River.

One of the most extensive and well-preserved collections of dinosaur footprints in North America.

This ancient trail has claimed the lives of over 2,000 people.

This oasis-like spring in the Sonoran Desert is home to unique, endangered species.

This remote desert watering hole has a connection to a curious chapter of American history.

Concrete crosses scattered across the Arizona scrubland which were used to align spy satellites.

The largest and most well-preserved petroglyph site in the Verde Valley.

A cabinet of curious mathematical models and old calculators.

The lost ruins of the forgotten ferry lie hidden beneath the silt.

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