In 1888, two cowboys spotted something strange at the base of some rocky reddish-yellow cliffs in southwestern Colorado. There, carved into the side of a plateau, was a hidden village of buildings and towers filled with empty windows. The men climbed down to explore the strange cliff dwellings and found hidden staircases and hundreds of rooms, some filled with children's toys, bowls, axes--and even skeletons Who were the mysterious people who had...