A great site to see if you''re in Mexico City are the impressive Teotihuacan pyramids. So that you can fully appreciate the awesome scale of the site, make sure you wear shoes suitable for walking and climbing on uneven terrain and take a bottle of water, sunblock and a hat. Get there early so you can enjoy a full day (you need it if you want to see everything).
The immense Pyramid of the Sun ranks among the biggest in the world, although a climb to the top of the slightly smaller Pyramid of the Moon offers the best view of the site, due to the difference in ground level. A climb to the top of either pyramid will be rewarded with a stunning view and is well worth it.
There is an on-site museum which diplays artifacts found on the site, and beneath the glass floor of the main hall, there is a scale model of the city which originally cover 20 sq km.
At opposite end of the site there is the Temple of Quetzalcoatl, beautifully decorated with carvings of masks of the serpent Quetzalcotl and a God thought to be rain god Tlaloc.
The Quetzalpapalotl Palace complex, near the moon pyramid has many fine carvings and murals.
There are many organised tours to the Teotihuacan from Mexico City, but be prepared to pay from $30. Much cheaper is getting the bus from the North Bus terminal -Autobuses Teotihuacan run a service half hourly approx. That way your whole trip, including entrance fee shouldn''t be much more than $10.