The Templo Mayor Project exists because of an accident. In February 1978 workers from the Compania de Luz y Fuerza, laying cable behind the Metropolitan Cathedral, hit the Coyolxauhqui monolith. The location of the great temple had been argued over for a century; the disc ended the argument. The Instituto Nacional de Antropologia e Historia constituted the Proyecto Templo Mayor within weeks, under Eduardo Matos Moctezuma, and it has run ever since.
The decision that shaped everything afterwards was to excavate the whole precinct rather than to lift the monolith and close the trench. That meant demolishing buildings in the most valuable square of the country, and it meant accepting that the earlier construction stages, which the Spanish demolition had left largely intact underground, were the point rather than an obstacle.
The method that came out of it is the reason the project is cited here. Each offering is excavated as a unit, its stratigraphic position recorded, its contents catalogued object by object, and the whole published individually. That is slow, and after nearly five decades the project has published more than two hundred of them. It also means that any claim built on this material can be taken back to a record and checked, which is a thing that cannot be done with a sentence in a sixteenth-century chronicle. Leonardo Lopez Lujan, who has directed the project since the 1990s, wrote the standing analytical treatment of the offerings themselves.