The Pyramid of the Sun at TeotihuacanBuilt in several stages beginning in about 100 C.E., the Pyramid of the Sun has sides measuring 700 feet long and 200 feet high. Originally it was covered with lime plaster decorated with brightly colored murals. Smaller pyramids surround it in what was the heart of the bustling city of Teotihuacan. (© age fotostock/SuperStock)