Graphical scale discrepancies. Each object (city, improvement, unit, bonus, route, feature) fills its square so it is visible. We adjust to the fact that an infantryman towers over buildings like Godzilla, but sometimes it jars. I'm not asking for google earth here, just a layer of zoom at which scales all match. When you are zoomed out you see things as through binoculars, one thing at a time. When you zoom in you see them together in proper relative scale. At some point it just transitions, like the music changing.