Faced with the peculiar question, "What is a film?" or "What is the nature of cinema?" the most obvious starting point may well be the most obvious fact about film: a film is something that we see. Things seen are, necessarily, spatial. But reasonable as it seems to insist then that a film must be a spatial object, one cannot stop there. For while other spatial objects merely occupy a position within space accessible to our vision, a film also provides its own space to replace that of our normal visual field. My concern here is to describe clearly this peculiar space that cinema presents for our experience—what I call cinema space.