The first section opened on 17 July 1871 from Moabit through Gesundbrunnen, Central-Viehhof (now Storkower Straße), Stralau-Rummelsburg (now Ostkreuz), Rixdorf (now Neukölln) and Schöneberg (later Kolonnenstraße, at the side where there is the new Julius-Leber-Brücke) to Potsdamer ring station, an annex of Potsdamer station.
From there, trains returned in the opposite direction.
 The line crossed the Anhalt Railway (and later the Royal Prussian Military Railway) on bridges.

With the opening of the section from Schöneberg through the still-independent city of Charlottenburg (now Westend station) to Moabit on 15 November 1877, the ring was complete for freight and long distance trains, while the suburban trains running on the Ring would still visit and reverse at Potsdamer station in the city centre,  turning north from the ring, running in parallel to the Berlin–Potsdam–Magdeburg Railway.
This section from the actual ring into the Potsdamer ring station became known as the Südringspitzkehre (Southern ring switchback or hairpin turn), reflecting the need for trains to reverse there to continue their trip around the ring.
Passengers could change at the Kolonnenstraße station across the platform to continue to ride on the Ring without going all the way to the Potsdamer Ringbahnhof.

From 1 January 1872, freight was carried on the line to freight yards separate from the passenger stations.
The line was electrified in 1926.
In 1930, ring line operation was combined with the Stadtbahn and suburban services as the Berlin S-Bahn.

Since the trains were pulled by steam locomotives, they had to be refilled with water and coal and serviced at relatively short intervals; this was possible by reversing at Potsdamer Bahnhof.
Even after electrification, the management of the railway company wanted to spare the passengers the need to change at the Papestraße or Schöneberg stations to an already well-filled train coming from the suburbs to reach the city centre.
Originally, there were not even the necessary rails for continuing on the Ring between Schöneberg and Papestraße stations.

The Reichsbahn planned to replace the level crossings between the Ring and Südringspitzkehre by over- and underpasses together with the building of the north-south S-Bahn line in the late 1930s, but this was omitted as one of many planned changes after the proclamation of Hitler's Welthauptstadt Germania on 30 January 1937.
In World War II, the Potsdamer  and Anhalter stations were heavily bombed; the Südringspitzkehre was closed in 1944 and was never reopened.
The first section opened on 17 July 1871 from Moabit through Gesundbrunnen, Central-Viehhof (now Storkower Straße), Stralau-Rummelsburg (now Ostkreuz), Rixdorf (now Neukölln) and Schöneberg (later Kolonnenstraße, at the side where there is the new Julius-Leber-Brücke) to Potsdamer ring station, an annex of Potsdamer station. From there, trains returned in the opposite direction.  The line crossed the Anhalt Railway (and later the Royal Prussian Military Railway) on bridges.
With the opening of the section from Schöneberg through the still-independent city of Charlottenburg (now Westend station) to Moabit on 15 November 1877, the ring was complete for freight and long distance trains, while the suburban trains running on the Ring would still visit and reverse at Potsdamer station in the city centre,  turning north from the ring, running in parallel to the Berlin–Potsdam–Magdeburg Railway. This section from the actual ring into the Potsdamer ring station became known as the Südringspitzkehre (Southern ring switchback or hairpin turn), reflecting the need for trains to reverse there to continue their trip around the ring. Passengers could change at the Kolonnenstraße station across the platform to continue to ride on the Ring without going all the way to the Potsdamer Ringbahnhof.
From 1 January 1872, freight was carried on the line to freight yards separate from the passenger stations. The line was electrified in 1926. In 1930, ring line operation was combined with the Stadtbahn and suburban services as the Berlin S-Bahn.
Since the trains were pulled by steam locomotives, they had to be refilled with water and coal and serviced at relatively short intervals; this was possible by reversing at Potsdamer Bahnhof. Even after electrification, the management of the railway company wanted to spare the passengers the need to change at the Papestraße or Schöneberg stations to an already well-filled train coming from the suburbs to reach the city centre. Originally, there were not even the necessary rails for continuing on the Ring between Schöneberg and Papestraße stations.
The Reichsbahn planned to replace the level crossings between the Ring and Südringspitzkehre by over- and underpasses together with the building of the north-south S-Bahn line in the late 1930s, but this was omitted as one of many planned changes after the proclamation of Hitler's Welthauptstadt Germania on 30 January 1937. In World War II, the Potsdamer  and Anhalter stations were heavily bombed; the Südringspitzkehre was closed in 1944 and was never reopened.
Berlin Ringbahn