The tilma of Guadalupe, bearing the image of the Virgin as seen by St. Juan Diego in 1531, continues to mystify scientists, historians, and theologians. No other image in recorded history has had such a radical, profound, and global evangelization and unification of peoples – nearly nine million Indian converts to Christianity within a decade. This talk looks at the phenomenon of this sacred cloth: its history, iconography, reputation for miracles, inexplicable preservation, and hidden secrets that are slowly unfolding for the modern world.