The Sun Pyramid was extensively
excavated in the first decade of this century by Leopordo Batres. Since
that time, two tunnels have been excavated into the core of the pyramid,
providing more information about its chronology and substructure. Another
extensive excavation by INAH, directed by Eduardo Matos Moctezuma in 1992-93,
exposed more of the pyramid complex, especially on its north and east sides.
As originally built, the Sun Pyramid was approximately 215 by 215 m at the base, and about 63 m high. It was significantly enlarged at least twice in later periods, resulting in a final size of 225 m along each side. The pyramid was located on the east side of the Avenue of the Dead in the northern half of the city. If the area of monumental construction between the Moon Pyramid and the San Juan Canal is regarded as the central zone of the city, the Sun Pyramid is located at its middle. In addition to its geographic centrality, the importance of the pyramid is indicated by a cave located under the structure. It is believed by certain scholars that the cave was used for ritual activities, and why the pyramid was constructed where it is today.
The pyramid was actually reconstructed as five stepped platforms. However, the forth platform seems to have been erorneously reconstructed by Batres early this century. The pyramid originally consisted of four stepped platforms, a surmounting temple, and the Adosada platform, which was built over what was originally the principal facade of the pyramid. No information about the temple itself is available, since, along with the upper-most portion of the pyramid, it has been completely destroyed.