The 66 Lakes Trail is a 400 km (249 miles) or so hiking/cycling trail that begins and ends in Potsdam and runs the circumference of the nature areas around Berlin. The landscape varies throughout this trek, which is broken into 17 stages, with options for public transport and nightly accommodations along the way.
Beside the lakes the trail is named for, the scenery changes from deciduous to coniferous forest, from picturesque villages to the castles and palaces of Potsdam, and from grassy heaths to burbling rivers. If a greater sense of the landscape that surrounds one of the world's most influential cities is high on your agenda, why not try a leg of the trail? You'll enjoy the hiking (best tackled in the summer) and you'll get a more authentic sense of Germany and its people than those top ten lists that litter your newsfeed.
Check the included websites for more specific details on each stage and which may best fit your ability, itinerary and sense of adventure.