The basilica of Guadalupe on Tepeyac hill, at the northern edge of the valley, receives more pilgrims than any other Catholic shrine in the Americas, and the account attached to it is that in December 1531 the Virgin appeared to an indigenous man, Juan Diego, spoke to him in Nahuatl, and left her image on his cloak.
The historical questions are old and were raised from within the church rather than outside it. Stafford Poole's study traces the documentary record and finds no contemporary evidence for the apparition, with the principal Nahuatl narrative dating from the following century and the earliest sources describing a cult without the story. The Franciscans who had evangelised the valley were openly suspicious of the shrine in the sixteenth century, on the grounds that indigenous people were venerating an image at a site associated with a mother goddess of the previous religion. The church has canonised Juan Diego and treats the tradition as authentic; the historical debate continues alongside that.
The relation to earlier practice is likewise argued rather than settled. Tepeyac is reported in colonial sources as a place of pre-conquest worship, and the identification with a specific goddess is asserted in some of those sources and doubted in others.
What is beyond dispute is the shrine's function. Guadalupe became the emblem of Mexican national identity, carried on the banner of the independence rising in 1810 and by farm workers organising in California in the 1960s.