Teotihuacan was the largest pre-Columbian city in the Americas. The city's broad central avenue, called "Avenue of the Dead", is flanked by impressive ceremonial architecture, including the immense Pyramid of the Sun (second largest in the New World after the Great Pyramid of Cholula) and the Pyramid of the Moon. Further down the Avenue of the Dead is the area known as the Citadel, containing the ruined Temple of the Feathered Serpent. Feb. 22, 2008. (ivan gonzalez)