Why was Bonn chosen as (West) Germany's new capital after WWII? Was there a reason not to choose Berlin? And: Why Bonn? There are so many German cities that are bigger or seemed more suitable nowadays (e.g. Hamburg, Frankfurt, Heidelberg, Munich, Aachen, Hannover, Köln)? And: who chose Bonn - the allied forces, the Bundestag & Bundesrat, someone else?

(note: sources in German are fine, I am fluent in both English and German)