First of all, the best thing you need is a Berlin ABC day pass. Because you travel from Potsdam by bus to Sacrow. It is best to get off at the castle. This old castle with its ambience and the view of the Havel has been carefully renovated. From time to time there are also exhibitions. Through the old garden you reach the Heilandskirche. Back to the castle, follow the road along the old villas in the direction of Kladow. The riverside path begins behind the last houses in Sacrow. Here, along the Havel, you can see the church of Peter and Paul and the Pfaueninsel with its historical buildings on the other side. At the end of the riverside path in Kladow, the road continues to Alt Kladow. From here you board the BVG ferry to Wannsee and when you arrive on the other bank of the Wannsee, take the S Bahn back to Potsdam or back to the Berlin districts.