The city of Mexico-Tenochtitlan dates back to as early as 1325. The old city that is now simply referred to as Tenochtitlan was built on an island in the Valley of Mexico. According to a legend, the Mexicas' principal god, Huitzilopochtli, indicated the site for Mexico City to be built with a golden eagle perched on a prickly pear devouring a rattlesnake.