On the 9 November 1989, the Border separating Western from Eastern Germany was was opened, allowing citizens from both west and east to cross freely through checkpoints.

The wall was built a wall in the dead of night on 13 August 1961 by communist East Germany and for 28 years kept East Germans from fleeing to the West.
Why was the wall built?
At the end of World War II, the Allied powers divided conquered Germany into four zones, each occupied by either the United States, Great Britain, France, or the Soviet Union. The same was done with Germany's capital city, Berlin.
In 1949, the three zones occupied by the United States, Great Britain, and France combined to form West Germany (the Federal Republic of Germany). The zone occupied by the Soviet Union formed East Germany (the German Democratic Republic).
This same division into West and East occurred in Berlin, a major city in Germany, located located in East Germany. The split of Berlin resulted in an island in the midst of the sea of East Germany.
The Berlin Wall Goes Up
Just past midnight on the night of 12-13 August 1961, the Berlin Wall was built around West Berlin