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.

See massive fossils that are over 200 million years old in northeastern Arizona.

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

The same security that protects our nukes accidentally protected a gentle herd of antelope.

The high point on the 16th president's eponymous roadway is marked by a massive version of his head.

Long before guestbooks and hotels, frontier travelers signed their names on this rock face.