You could get the yahoo home page_type in yahoo .com
then at the bottom of page click yahoo international or other yahoos
pick the german yahoo deutsch yahoo
then click immobilien _top of page_in german_should manage with a dictionary
The main newspapers also have property sections. For example, http://immobilienmarkt.sueddeutsche.de/ is from the Sueddeutsche Zeitung. Not sure what's the main paper in Hamburg, but I'm sure google will come up with something.
Note, all these are in German. Dunno how much of it is also available in English.