Aim for a dry day to Potsdam which is on an easy S-bahn ride from Berlin. Follow the signs to the bike renting place upon leaving the station - it's only five minutes walk on the way to Potsdam centre. The 17km (11 miles) bike ride takes you through beautiful Potsdam, UNESCO Heritage site, to Sanssouci, baroque palace of Friedrich the Great, rococo OTT New Palace and myriad of other architectural curiosities in Sanssouci's opulent landscaped grounds. The trail continues through the stunning New Gardens with lakes and more palaces before crossing the Glienicke bridge immortalised in cold war films. Babelsbeg Park with its German film heritage is the oasis of tranquillity before the full circle is completed. Beautiful!
Google map: bit.ly/RsKmaE