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

The site of a defunct mill, that once supplied marble for the construction of the Lincoln Memorial.

A mass grave for victims of an airline disaster that led to much-needed safety improvements for commercial flights.

This National Natural Landmark is one of the best examples of a “mass wasting” in the world.

Crafted in 1911, this steam locomotive spent its entire working life in Flagstaff.

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

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

A little-known hot spring haven right below the highway.

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

The site of the gruesome massacre—and maybe cannibalism—of five men, a tragedy that made Alferd Packer infamous.

Take a dip in the world's largest mineral hot springs pool.

Even in death, he's still your huckleberry.

An eatery for UFO seekers on the Extraterrestrial Highway.

A small canyon with petroglyphs and a seasonal waterfall, only a short hike from the remnants of old Route 66.

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

One of the largest, oldest, darkest, quietest motel rooms in the world.

This sign designates the road that leads to the infamous Area 51.

The hallowed remains of a 900-year old Ancestral Pueblo great house.

An artificial crater field that trained astronauts for lunar exploration.

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

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.

A coal fire has been burning underground here since 1896.

A quiet rock and botanical garden is the beautiful centerpiece of Fort Lewis College.