From J.N. Tylenda’s Saints and Feasts of the Liturgical Year:
The shrine of Our Lady of Guadalupe, on the outskirts of Mexico City, is the most famous shrine of our Lady in the Western Hemisphere, and today we commemorate her appearances to a native Mexican convert, St. Juan Diego, on Tepeyac Hill. On December 9, 1531, our Lady appeared to him and asked that a church be built on the site, and on December 12 she again appeared and urged him to take her message to the bishop. To offer proof that he was our Lady’s messenger, she told him to gather the flowers he found blooming there in mid-December. When Juan Diego stood before Bishop Juan de Zumárraga, he opened his cloak, and as the flowers cascaded to the floor, those present saw on the rough cloth an image of our Lady—the image still preserved at the shrine. The first sanctuary was built in about 1533; the second was begun in 1556; and the third was built in 1695. The present basilica dates from 1976. In 1746, Our Lady of Guadalupe became the patroness of Mexico, and in 1754 Pope Benedict XIV established December 12 as the feast. In 1945, when Pope Pius XII was speaking of Our Lady of Guadalupe, he called her “Queen of Mexico and Empress of the Americas.” The pope went on to say that the image on the cloak was done “by brushes that were not of this world.” The prayer in the Mass today affirms that by the Virgin Mary’s appearance at Tepeyac, God has brought blessings to the Americas (273-294).