The Great Wall! People come from the ends of the earth to see it. It is one of the wonders of the world, a unique, almost mythical, and in some sense unfathomable creation. The Chinese constructed it, with interruptions, over the course of two thousand years. They commenced when the Buddha and Herodotus were alive and were still building it when Leonardo da Vinci, Titian, and Johann Sebastian Bach were at their labors in Europe.