I refer specifically to the fact that a large part of the city was built south of a river and only a smell part to the north. It seems a bit strange to me.
Like most cities that focus on sea trade, it was built around the sea port, i.e. th Golden Horn. http://en.wikipedia.org/wiki/Golden_Horn That's is simply where the business was done. http://en.wikipedia.org/wiki/Golden_Horn#mediaviewer/File:Halic.png
But while it made sense to use both sides, the south side was a whole lot more defensible, this was the Fall http://en.wikipedia.org/wiki/File:Siege_of_Constantinople_1453_map-fr.svg
Or if you look at this map it is even clearer: http://en.wikipedia.org/wiki/Walls_of_Constantinople#mediaviewer/File:Map_of_Constantinople_%281422%29_by_Florentine_cartographer_Cristoforo_Buondelmonte.jpg
That parth in the north side, Galata, or Pera, was originally not part of the city, although integrated early enough: http://en.wikipedia.org/wiki/Galata
