Today, el doce de diciembre, is a holiday for an important Catholic symbol in Mexico. Guadalupe is represented as a manifestation of the Virgin Mary in the Americas. Guadalupe is also a symbol of Mexico. Read below about Guadalupe's first appearance in Mexico in 1531,
"According to traditional Catholic accounts of the Guadalupan apparitions, during a walk from his village to the city on the early morning of December 9, 1531, Juan Diego saw a vision of the Virgin - a young girl of fourteen to sixteen, surrounded by light- at the Hill of Tepeyac. Speaking in Nahuatl, the Lady asked for a church to be built at that site in her honor. When Juan Diego spoke to the Spanish bishop, Fray Juan de Zumárraga, the bishop asked him for a miraculous sign to prove his claim. The Virgin asked Juan Diego to gather some flowers at the top of the hill, even though it was winter when no flowers bloomed. He found there Castilian roses, gathered them, and the Virgin herself re-arranged them in his tilma. When Juan Diego presented the roses to Zumárraga, the image of the Virgin of Guadalupe miraculously appeared imprinted on the cloth of Diego's tilma."
http://en.wikipedia.org/wiki/Our_Lady_of_Guadalupe