In 2005, David Roberts and two of his mountaineering friends caught sight of what appeared to be a granary beneath an overhanging cliff a thousand feet above a Utah ranch. After rappelling down the cliff, Roberts and his companions discovered a settlement--and a mystery. This enormous granary was large enough to hold fifty-seven bushels of corn, weighing a ton and a half. Yet Roberts and his friends--some of the most experienced climbers in the world--had enormous difficulty reaching the site. In fact, they were the first people to reach the remote site in more than seven hundred years. How could the ancient natives have managed to lug so much grain up this sheer cliff, especially considering there is no conclusive evidence that they possessed rope technology? For more than 5,000 years the Ancestral Puebloans occupied the Four Corners region. Just before 1300 AD, they abandoned their homeland in a migration that remains one of prehistory's greatest puzzles. Northern and southern neighbors of the Ancestral Puebloans, the Fremont and Mogollon likewise flourished for millennia before migrating or disappearing. Fortunately, the Old Ones, as some of their present-day descendants call them, left behind awe-inspiring ruins, dazzling rock art, and sophisticated artifacts ranging from painted pots to woven baskets.