Comment by Aldipower

Hamburg is one of the greenest cities in the world (summertime). Not too far from the Stadtpark you'll find the Olsdorfer Friedhof, which is the largest "park cemetery" in Europe. If the Stadtpark is still too busy for you, despite it actually never is really, the cemetery is even quieter to find some rest and a refreshing walk. I know it sounds strange, but I mean it. :-)