The Pyramid of the Sun is the largest building in Teotihuacan and one of the largest in Mesoamerica. Found along the Avenue of the Dead, in between the Pyramid of the Moon and the Ciudadela, and in the shadow of the massive mountain Cerro Gordo, the pyramid is part of a large complex in the heart of the city.

The name Pyramid of the Sun comes from the Aztecs, who visited the city of Teotihuacan centuries after it was abandoned; the name given to the pyramid by the Teotihuacanos is unknown. It was constructed in two phases. The first construction stage, around 100 C.E., brought the pyramid to nearly the size it is today. The second round of construction resulted in its completed size of 224.942 meters (738 feet) across and 75 meters (246 feet) high, making it the third largest pyramid in the world,[6] though still just over half the height of the Great Pyramid of Giza (146 metres). The second phase also saw the construction of an altar atop of the pyramid, which has not survived into modern times. The Adosada platform was added to the pyramid in the early third century, at around the same time that the Ciudadela and Temple of the Feathered Serpent, Teotihuacan Pyramid of the Feathered Serpent were constructed.

Over the structure the ancient Teotihuacanos finished their pyramid with lime plaster imported from surrounding areas, on which they painted brilliantly colored murals. While the pyramid has endured for centuries, the paint and plaster have not and are no longer visible. Jaguar heads and paws, stars, and snake rattles are among the few images associated with the pyramids.

It is thought that the pyramid venerated a deity within Teotihuacan society, however, little evidence exists to support this hypothesis. The destruction of the temple on top of the pyramid, by both deliberate and natural forces prior to the archaeological study of the site, has so far prevented identification of the pyramid with any particular deity.