I just got back from Teotihuacan where I climbed a couple of Aztec pyramids. It is literally a breathtaking experience. It was on these pyramids that the Aztecs sacrificed people. There are two main pyramids, the Sun and the Moon, and a few other smaller ones. One of them I believe is for Quetzalcoatl, who was a Toltec priest who became a god. Wikipedia has an article on Quetzalcoatl, although it differs from what I have heard from villagers living in what used to be the seat of the Toltec civilization.