The legend says that they wandered for centuries all over Mexico looking for a suitable place to build their empire. Such a place, the wise men of the Aztecs said, would be showed to them by an eagle poised on a nopal, with a snake in its claws. And so for centuries the Aztecs wandered, looking for such an eagle, and finally at about the year 1200 of our own era, as they reached the valley of Anahuac, in Central Mexico, they stopped in wonder on the shores of Lake Texcoco. There on a small island was a nopal and on that nopal there stood an eagle with a serpent on its bill. Their journey had come to an end and the Aztecs knelt down and thanked their gods for their good fortune, and they built a city on that island, which they called Tenochtitian, the embryo of the Mexico City of today.