The U12 is a former Berlin U-Bahn line. It existed between 1993 and June 2003, as a peak-time and night line between Ruhleben (today U2) and Warschauer Straße (today U1) stations. The line was withdrawn in June 2003 and more night-time lines were introduced, which is U1, U2, U3 (from 2006), U5, U6, U7, U8 and U9. On 22 June 2020, the U12 line was reinstated due to maintenance repairs of the U1, U2 and U3. The U12 runs between Kottbusser Tor (via Wittenbergplatz) to Ruhleben station. It is expected to run until 9 August 2020. From Wikipedia