The Aztecs saw an eagle sitting on prickly pear cactus by the side of a lake. The eagle was eating a snake. The Aztecs took this as a sign to make it their new capital. Thus, Tenochtitlan was born. After 1473, Tenochtitlan was merged with Tlatelolco to form a twin city. Four large districts and several small ones made up the city. Two pyramids stood in the middle of the city. The pyramids were built for the gods Tlaloc and Huitzilopochtli. The palaces of the rulers stood near the temple district.
The Aztecs were under the thumb of the mighty Tepanecs of the Azcapotzalco Empire. King Itzlcoatl shook off the rule of the Tepanec in the fifteenth century. He united Tenochtitlan, Texoco and the new Tepanec centre of Tlacopan under a single rule. His nephew Moctezuma I followed in his footsteps. He conquered the region of Chalco or present day Mexico City and even territories as far as the Gulf Coast. His successors conquered the neighbouring state of Tlatelolco. The image of the eagle eating a snake has become part of the emblem of Mexico.