From Catholic News Agency:
Those who visit the chapel of the Our Lady of Lourdes shrine in the city of Alta Gracia in Córdoba province, Argentina, witness a phenomenon that has no explanation: In the niche that is part of the altarpiece above the altar, an image of the Virgin Mary can be seen although without a doubt the space is empty — there is nothing there.
According to the Argentine news agency AICA, what is seen is not a flat image but rather a relief, a three-dimensional image with folds in the garment. It is also not a psychological illusion resulting from the exaggerated devotion of some pilgrims. Everyone — believer or not — sees it. Additionally, the image appears in photos taken there. A curious fact is that the image is clearly seen from the front door of the church and then fades as one slowly approaches the altar.