I visited this WHS in May 2014. I visited a number of parks in Berlin and my personal favourites there were Peacock Island and Charlottenburg Palace. However, I experienced the true OUV of this WHS in Potsdam's Sanssouci Park. Before entering the park I gazed at the strange false mosque housing the steam engine house. There's also a reconstructed windmill and several other buildings to visit in this megalomaniacal park. The highlight of my trip was the Chinese Tea House and it was worth popping inside to see its painted ceiling and chinaware. If you want to take pictures inside the Sanssouci Palace, New Palace or Chinese Tea House you have to pay an additional 3 euro camera fee. The Sanssouci Palace and Park is definitely the best palace/castle WHS I visited in Germany and a very close contender to France's Versailles. Definitely worth visiting and I wouldn't mind staying for a night or two to explore Potsdam better next time!