There are three in the area; Sol (pyramid of the sun) is the third largest pyramid in the world, Luna (pyramid of the moon) is slightly smaller than Sol, and the Feathered Serpent pyramid (I believe it is called the Temple of Quetzalcóatl). Also, there is the Avenue of the Dead and the Ciudadela (Citadel) in the area. See the following sites for more info:
http://archaeology.la.asu.edu/teo/
http://www.differentworld.com/mexico/places/mexico_city/teotihuacan.htm