MACHU PICCHU, PERU – The Incas built this mysterious city here, it is told, to be closer to the gods. It was placed so high in the clouds, at 7,700 feet, that the empire- raiding Spaniards never found, or destroyed, it. Today, visitors to Machu Picchu see well-preserved ruins hidden among the majestic Andes: complete with palaces, baths, temples, tombs, sundials, and agricultural terraces, and also llamas roaming among hundreds of gray granite houses. But they won't find too many bowls, tools, ritual objects, or other artifacts used by the Incas of the late 1400s. To see those, they have...