Stone Aztec sculpture of a xiuhcóatl or fire serpent, at Tenayuca, a lakeside town north of the island-city of Tenochtitlan and the site of a famous large dual pyramid (in the background), one of the few which still stand; extensively excavated, it was enlarged 8 times during the Toltec, Chichimec and Aztec periods, ending up twice its original size by the time of the Spanish Conquest.