It’s impossible to be certain why Ancestral Pueblo people decided to move into the cliff-side alcoves and build elaborate and expensive structures like Cliff Palace. Whatever the reasons, around 1200 CE, some of the people then living on Mesa Verde moved away from their mesa top fields and into the cliffs and alcoves, often re-occupying sites that had been inhabited by their ancestors 600 years earlier. This is probably the case with Cliff Palace, where archeologists find evidence of earlier buried structures.