“Kottbusser Tor is a Berlin U-Bahn station located on the U1, U3 and U8. Many Berliners use the affectionate term Kotti.
It is located in central Kreuzberg. The area has a bad reputation for the relatively high, mainly drug-related crime rate, instances of which have recently become quite rare in most other parts of the district. The original Kottbusser Tor was a southern city gate of Berlin; the road through the gate led via the Neukölln suburb to the town of Cottbus.
The station on the first Berlin U-Bahn line from Potsdamer Platz to Stralauer Tor was opened on 18 February 1902 on a viaduct above Skalitzer Straße. When in 1926 the U8 was built, a new two-level station was constructed 100 metres (330 ft) westwards to allow both lines to meet in one location, and the original station was demolished.
It was directly hit on 26 February 1945.” (source)