I was walking down a street in the Boca neighborhood of Buenos Aires, when I realized someone was spying on me. Police? A theif? An assassin? I turned around slowly so as not to call his attention. His? What if it were a woman? No, it was a man. He was peering at me from behind a door--painted on the wall! I sighed with relief and took out my trusty Apple I pad and took his picture.