Teotihuacan, the "place where gods are made", is located 31 miles northeast of Mexico City. Experts believed the city's builders came about 2,000 years ago, their culture based on worship of the rain god. The pyramids of the Sun and the Moon, the Ciudadela, with its Temple of Quetzalcoatl (the Plumed Serpent) and the Palace of Quetzalpaplotl (Plumed Butterfly) are the major constructions along the site's nearly mile-long main thoroughfare, the Avenue of the Dead. It's a good idea to begin your visit at the museum built next to the Sun pyramid to get an overview of the site.