The Berliner Mauerweg rings the whole of former West Berlin, so about 50 km runs through the city and roughly 110 km is forest, lake and farmland. The three sections with the highest concentration of surviving Wall and border sites total about 19 km. Here is how to pick a section by what is still standing on it, not by what looks convenient on a map.

Everyone on the summer S7 says they are going to Wannsee, and they are all going to different places: a 1907 sand beach, an island of free-roaming peacocks, a villa shore that carries the heaviest history in Berlin, and a lake ferry that runs on a normal BVG fare. Here is how the geography actually works, and how I would combine it.