This excellent photo can be found at Ephemeral New York: an 1884 shot of the corner where the Flatiron building now stands. A big, clear, detailed photo like this is a rarity.
The 1902 Flat Iron building is iconic, as recognizable as the Eiffel Tower (though on a smaller scale) or Trafalgar Square in London. Film makers use it to establish geography almost as a matter of course. But look at this corner before all that (clicking on the image will take you to the full-sized version at Ephemeral New York).