Pyramid of the Sun
Likely used as a religious and sacrificial center, the Pyramid of the Sun is the largest structure on the site and third largest pyramid in the world after Cholula near Puebla Mexico and Cheops in Egypt. When the site was rediscovered early in the 20th century, the pyramids appeared as hills of stone rubble with trees and plants growing up from the rocks. The temple atop the Pyramid of the Sun had long vanished from the towering structure.