I was watching "The Great Dictator", and in the scene in which Hynkel is throwing a great inflatable globe about, it struck me that even with the technology of flight circa 1940, it still must be really difficult to get the landscape you see from a plane into context enough to draw an accurate map. We had fairly spot-on maps then, though. This got me thinking about ancient maps, too. I know they're often inaccurate, but I'd like to know the techniques ancient (and more recent) cartographers would use. Small-scale maps I can understand, but what about mapping a whole country or continent?