Why did the Mesa Verde Indians choose to live in cliffs?

Dr. dig responds:
The cliffs provided a natural shelter against the wind and the rain and the hot sun. In a landscape that had few raw building materials, the cliffs were chosen out of good common sense. Where else were people going to live and protect themselves from the dangers of the desert? If I were to choose between the open desert and the solid wall of a cliff face, I think I would choose to build my house against a good solid wall with nothing scary behind me!