For nearly a century-and-a-half, archaeologists have been studying Mesa Verde in hopes of deciphering what happened to the Ancestral Puebloan people who lived and thrived there for so long. For many, it remains one of the great mysteries in the history of North America. On this episode of Lost Highways, we'll explore the way that historians and archaeologists try to solve these kinds of mysteries, and how they know what they say they think they know. Where does that confidence come from? How confident are they, actually? And what happens when what we think we know changes?