MEXICO CITY.- When looking for archaeological elements of the first constructive stage of Tlatelolco, to confirm a foundation date, researchers of the National Institute of Anthropology and History (INAH) found at Templo Mayor (Main Temple) a staircase that gave access to a shrine that dates from the earliest architectural stage, as well as a stuccoed floor, probably dated between 900 and 1200 of the Common Era.

The finding may confirm the moment when the first building of Tlatelolco, the twin city of Tenochtitlan, was established, informed archaeologist Lucia Sanchez, director of the archaeological zone.

According to ethno-historical sources such as official chronicles of Fray Diego de Duran and Padre Acosta, the foundation of Tlatelolco took place in 1337, while Tenochtitlan was founded in 1325. Other sources like Historia Tolteca-Chichimeca and Mapa de Sigüenza, report that Tlatelolco was created before or at the same time as Tenochtitlan.

The INAH researcher mentioned that the finding of the staircase adds up to those of the past years. Ceramic fragments, obsidian pieces and small animal bones, part of the pyramid’s filling were found as well.

As the skin of an onion, Templo Mayor of Tlatelolco was studied inside out, taking advantage of a tunnel created in Prehispanic times that goes through the structure.

Lucia Sanchez recalled that between 1992 and 1993, during excavations headed by archaeologist Salvador Guilliem, a complete staircase was found in the occidental façade of the pyramid, at the Stage 1a, as well as remains of another. In 2007, when the work was retaken, a third staircase, also broken, was located in Stage 1b.

In 2009, another exploration from the upper part of the structure took place, which led to finding at 7.5 meters depth, a stucco floor and a small plaster with remains of red, black and blue pigments, as well as fragments of small polychrome braziers.

The archaeologist mentioned that between February and June 2011, 12.5 meters into the tunnel, the staircase that gave access to a shrine was discovered, as well as the continuation of the stuccoed floor located in 2009; the space was named Stage 1c, and could be dated in Post Classic period (950-1200 AD).

The chief of Tlatelolco Archaeological Zone continued mentioning that ceramics, obsidian –mainly small knives-, stone used for construction as well as for filling, and small animal bones were found.

“This material was used for filling; small mollusk shells from the lake were found, indicating this soil was used also for the filling”.

“These elements would correspond to the foundation of the city; according to ethno-historical sources, they would correspond to 1337, but could be older, from 1000 to 1200 of the Common Era”, commented Lucia Sanchez.

The archaeologist said that analysis is being conducted to verify if the 3 stages (1a, 1b and 1c) correspond to different constructive stages or they are just attachments to the temple of Tlatelolco.

She detailed that in order to obtain precise information to complement excavation data, different studies take place on material found in the past, such as ceramics, charcoal and shell, with the collaboration of the INAH Sub Direction of Laboratories and Academic Support and the Paleomagnetism Laboratory at UNAM Institute of Geo Physical Investigations.

“Some analyses will imply Carbon 14, as well as thermoluminescence and archaeomagnetic dating, methods used to determine temporality of ceramic pieces and stuccoed floors”, she explained.

Results will allow, according to Tlatelolco Project objectives, to establish comparisons between Tlatelolco and Tenochtitlan in their earliest stages.

Templo Mayor of Tlatelolco exploration is part of an archaeological project that began in 1987 headed by archaeologist Salvador Guilliem Arroyo with collaboration of researchers Patricia Ledesma, Alejandro Rivera, Claudia Nicolas, Maria de Jesus Alvizar and Lucia Sanchez de Bustamante.