The eagle was the symbol of the mighty Roman Empire, of the Roman emperors such as Caesar, as well as mythological symbol representing the Greek god Zeus. It appears frequently in the ancient Greek art, Hellenistic art, and Roman art. Eagle Clutching the Snake appears on some ancient Greek and Roman coins. The eagle is also symbol of the German and American states. The legend of the Eagle Clutching the Snake is also found in Mexico. Originally nomads from the north or west of Mexico, the Aztecs were led to the Valley of Mexico by their priests. They settled on the islands in the series of lakes which then filled much of the valley because it was there that they happened to spy an eagle standing on a cactus, eating a snake – the prophesied sign that this was the place to stop their wanderings. The Aztec capital, Tenochtitlán was founded on one of the islands in the first half of the 14th century. For half a century or more the Aztecs served the rulers of Azcapotzalco on the lake shore, which was gaining control over some of the dozens of rival stateless in the valley. Then, in the 15th century, the Aztecs rebelled against Azcapotzalco and became in turn the most powerful people in the valley. The eagle clutching a snake is the central insignia on the flag of Mexico. Tenochtitlán is now Mexico City.