Just another note that I watched it again a week or so ago with the commentary by cinematographer John Bailey, and there is quite a lot of discussion of Struss as a still photographer, pictorialist, and his place in the New York photography scene. Struss was responsible for the composite shots and multiple exposures, which were done by running the film two or more times through the camera with a matte box masking various parts of the frame.
It's also interesting to hear how sets were designed to create perspective illusions with slanting floors, walls and windows that tapered toward the background, and miniatures. The outdoor scenes were done with miniature buildings built to scale and crowds of midgets in the background.