Berlin Wall, wall 26 mi (42 km) long built in 1961 dividing East and West Berlin. Before 1961, many people fled East Germany by crossing from East to West Berlin. The wall halted this emigration. Between 1961 and 1989 over 70 East Germans were killed attempting to get past the Berlin Wall. In November 1989 the wall began to be dismantled after demonstrations for political reform erupted in East Germany.