Meet your private guide at your central Berlin hotel and travel in a Mercedes Vito taxi to Schloss Charlottenburg. During the 45-minute trip to Potsdam, drive through Wannsee on your way to Schloss Glienicke and the Glienicke Bridge, where spy swaps took place during the Cold War.
Continue on to Potsdam where your guide will explain how this scenic town served as the residence of Prussian kings and German emperors of the House of Hohenzollern for three centuries. Marvel at the majestic castle of Babelsberg. Visit the New Garden, a large park where the Marble Palace and Schloss Cecilienhof are located. Admire the lakeside Marble Palace and learn how Schloss Cecilienhof was the site of the Potsdam Conference where the leaders of America, Britain and the Soviet Union decided the future of Germany after WWII.
Afterward, head to the Russian colony of Alexandrowka and see 13 wooden houses built in the 1800s for the Russian singers of the First Prussian Regiment of the Guards. Then it's off to downtown Potsdam for a lunch break at a local restaurant (own expense). While downtown, see St Nicholas Church and the town hall, as well as the city palace that's home to the Brandenburg Parliament.
Finally, head to the Sanssouci Palace and marvel at its stunning Rococo architecture. Palaces are open on varying days of the week so your choice of palace will depend on which day you take your tour. You may, for instance, visit Neue Kammern or Neues Palais at Sanssouci Park instead of Sanssouci Palace (own expense). Being on a private tour means you can work with your guide to choose the attractions that most interest you and ask as many questions as you like about the sights you see. Keep in mind that since so much of this tour takes place in castles and parks, there's a fair amount of walking involved.
At the conclusion of your 7-hour scenic and educational tour of Potsdam, you'll be driven back in your taxi to your Berlin hotel.