Cuicuilco is dominated by a circular temple. This is clearly the oldest of such large scale construction in central Mexico. This is not as impressive as many other ruins in Mexico, but it is one of the most important ruins in all of Mexico and Central America. It is definitely a must see site. Cuicuilco is an often debated site among various groups who are studying archaeology. The major discussions seem to debate whether or not Cuicuilco is older than 10,000 years old. There are many web sites that you can go to if you wish to investigate this discussion. However, not much is known about this site which was partially buried by the volcano eruption and which has almost been completely covered by new building construction. This site, is commonly accepted as among the oldest in the Valley of Mexico. Parts of the large and complex site are buried by ash from volcanoes as recently as 300.A.D., while other parts are buried under volcanic ash that are said to have been dated as 8,000 years old. Most archaeologists do not support the 8,000 year old date. One eruption is actually carbon dated at about 30 AD. The major volcano which has deposited lava flows over the site of Cuicuilco is Xitle Volcano, which is part of the Ajusco range. Xitle's, deep and foreboding crater - 200 meters above ground, 3100 meters above sea level - lies just a couple of kilometers off the Ajusco highway. There are those who claim that 150 B.C. was the year of the great "consternation" that destroyed Cuicuilco. but actually "Xitle: He with the navel", according to scribe Alva Ixtlilxochitl, "opened the earth and swept everything in its path, on the day Ahui-Quiahuitl, in the year 8-Tecpatl," this translates into April 24 of 76 A.D." So, only three years before Vesuvias buried Pompeii. "The rivers of lava ran for several years, and thus was formed Tetetlan, "Place of Stones" and Texcallan, the "Home of the Rock." Nearby on the university campus is Cuatzontle a lateral vent of the celebrated Xitle volcano. We have enclosed some photos of this interesting vent on this page. Cuicuilco was abandoned at the time of the eruption of the volcano Xitle in about 30 A.D.. This was about the same time that Teotihuacan was beginning to develop. There are numerous discussions which claim that the destruction of Cuicuilco caused the growth of Teotihuacan. The massive circular pyramid is composed of three sloping tiers which are approached by a ramp and a stairway and it has a base 387 feet in diameter with a height of 75 feet. A small museum is on site and both the museum and site are free to the public. It is open from 9:00AM to 5:00PM. We were here December 1982, January 2004, and January 2005.