The Wannsee Railway is a suburban railway in Berlin running from Potsdamer Platz via the Ring line station of Schöneberg to Wannsee station on Großer Wannsee, a lake after which it is named. Today it is a section of the Berlin S-Bahn line S1.

The Ringbahn is a 37.5 km (23.3 mi) long circle route around Berlin's inner city area, on the Berlin S-Bahn network. Its course is made up of a pair of tracks used by S-Bahn trains and another parallel pair of tracks used by various regional, long distance and freight trains. The S-Bahn lines S41 and S42 provide a closed-loop continuous service without termini. Lines S45, S46 and S47 use a section of the southern and western ring, while lines S8 and S85 use sections of the eastern ring. The combined number of passengers is about 400,000 passengers a day. Due to its distinctive shape, the line is often referred to as the Hundekopf.