This city doesn't seem to be a real existing one, but in regard of the hills in the background and the architecture of the houses in the front, it is probably supposed to be in the South West of Germany (Black Forest region). Although this city is probably not real, I can see a little bit of various places in it, e.g. Heidelberg, Tuebingen, Rothenburg or Calw, but also a little bit of Zurich and Nuremberg, maybe with some notes of Mulhouse and Colmar in Alsace, Speyer in Palatinate and Marburg in Hesse.
