La Pyramide du Soleil est la troisième pyramide du monde par la taille, après celle de Cholula à Puebla et de Kheops en égypte.

Bâtie vers 100 après J.C., elle révèle une base d'environ 222 mètres de long de chaque côté. Elle s'élève à 70 mètres de hauteur et était coiffée, à l'origine, d'un Temple de bois et de chaume.

En 1971, des archéologues découvrirent un souterrain de 100 mètres menant d'un point situé à proximité du côté ouest de la pyramide, à une grotte en plein coeur de la pyramide, où ils mirent au jour des objets cultuels.

A l'apogée de Teotihuacán, l'enduit recouvrant la pyramide était peint en rouge vif.

In sheer size the Pyramid of the Sun is the largest pre-Hispanic building of its times (100-650 A.D.) and one of the most important in Meso America. Its name cornes from the fact that beginning in the sixteenth-century, accounts claimed that the sun god was worshipped at this immense monument. Large-scale exploration of it was undertaken in 1906 by Leopoldo Batres upon orders from then President Porfirio Díaz. The twin purpose was to emphasize the cultural wealth of the Mexican people expressed in their pre-Hispanic Works, and to celebrate Mexico's 100 years of independence in 1910.

Archaeological investigations at this monument indicate that its construction was carried out in a single operation, and show that its interior is solid and formed from sand and dirt fills. The tunnels seen on its sides have been dug by various researchers in order to learn something about its history and construction System.

Its erection got under way more or less in the Tzacualli phase (1-100 A.D.), and in the next phase (Miccaotli, 100-250 A.D.) 4 platform was added in front of its main facade and then, parallel to it, two Temples were built on its north and south sides. Three overlying levels of construction have been found.

The last and most recent can be seen at the base of the north, south and east sides of the pyramid, where one notes that the building rests upon a huge platform surrounded by a moat. The overall shape of the monument as seen today belongs to the building's penultimate construction phase. According to recent studies, there are errors in the reconstruction carried out early in this century, since it is shown with five terraces instead of the original four. The top of the pyramid was once crowned by a Temple where religious rites associaled with the deity to which this building was dedicated, were carried out.