The Berlin Wall was a barrier which divided Berlin into two halves- East Berlin and West Berlin, from the year 1961 to 1989. The wall stretched across  a length of 140 kms. It completely separated West Berlin from East Berlin until the Government decided to do away with it on November 9, 1989. On 13 June 1990, the Berlin Wall started getting demolished until 1992 when it was finally completed. https://en.wikipedia.org/wiki/Berlin_Wall