"We were searching for the last capitol of the great Inca Empire that had extended more than the length of Peru before the Spaniards came in the 16th century. With two Yale colleagues, a Peruvian soldier, and a mule train, I had investigated every rumor of a ruin. And now, camping beside the river at the base of a mountain called Machu Picchu, we were told of another ruin on the ridge above us."