How do you draw the map of the city at night? Technically speaking, a map is a horizontal projection "looking down" so the sky doesn't appear in the drawing. Yes, astronomical charts are maps of the night sky and recent satellite photographs show cities defined by their lighting of streets and roads at night, but I'm thinking of a different kind of night map.

For example, there is a wonderful map of Istanbul depicting the appearance of the Great Comet in 1577. On the lower part of the image there is a more-or-less conventional map of Istanbul depicting the historic peninsula to the right, Üsküdar to the left and Pera at the bottom, with the Bosporus running vertically and the Golden Horn horizontally. Then, just to the south of the peninsula (north in this map is down,) instead of the Sea of Marmara, the map introduces the night sky with the starts, the moon and the comet trailed by its long tail. It's a rather ingenious way to turn a horizontal projection into a vertical view. It seems as if the mapmaker chose this particular orientation--I can't remember any other map of Istanbul oriented this way--to be able to superimpose the sky over the expanse of the sea. And that is only the beginning of this question about orientation, since it triggers all sort problems. Just look at the Galata Tower towards the bottom of the drawing, shown in elevation but upside down.

(With thanks to my friend Elif Özgen that introduced me to this and other amazing images of Istanbul. Also, I must confess that I not only know preciously little about this map, but I have a low-resolution image so it's not so easy to look at it in more detail. And needless to say that I can't read the text at the top. Any help would be much appreciated.)