A: Manhattan, New York, New York, United States
Since 1989 conservators and art historians have known that hidden beneath the surface of Picasso's “Woman Ironing” preserved in the Solomon R. Guggenheim Museum, New York, is the upside-down ghost of another painting — a three-quarter-length portrait of a man with a mustache. The hidden image was first seen in photographs of this painting from Picasso's Blue Period (1901-1904) taken with an infrared camera in 1989.
On October 24, 2012 The New York Times published an article by Carol Vogel on this painting and the painting hidden underneath entitled "Under One Picasso, Another." From the standpoint of this database on the history of media what I find most interesting about this is the "interactive feature" published in association with the article entitled "Scratching the Surface, Two Picassos Revealed."
A very clever imaging program in the interactive feature invited the reader to "click and drag your mouse over the painting to see what was hidden beneath it." As I wiped the top image of the painting off with mouse strokes the painting underneath was revealed. I could also rotate the image and reset it back to the top layer.