Communist authorities seal off all roads between East and West Berlin, erecting a barrier of barbed wire and cinder blocks. The division of post-war Germany into four occupation zones left Berlin within the Soviet zone, and internally divided into East and West Berlin. For East Germans unhappy with life under communism, West Berlin became a gateway to the democratic West. By August 1961, approximately 2,000 East German refugees were streaming into the West every day, leading communist authorities to halt access to West Berlin. A high wall of concrete replaced barbed wire and cinder blocks, and East German border guards were ordered to shoot anyone crossing the wall. For the next 28 years, the Berlin Wall stood as the most tangible symbol of the Cold War–an iron curtain dividing Europe. Berlin remained divided until 1989, when East Germany opened its borders and the Berlin Wall was torn down.