<human>:  What is the history of the Berlin Wall?
<bot>: The Berlin Wall was a barrier that divided Berlin, Germany, from 1961 until 1989. It was constructed by the German Democratic Republic (East Germany) to separate East Berlin from West Berlin, and it was very closely guarded. The Berlin Wall served to prevent the easy movement of people between East and West Berlin, and it had a great symbolic importance for both sides. The Wall came to symbolize the Cold War and the Iron Curtain that divided Europe, isolating East and West. The Berlin Wall began to fall in 1989, and after several months of protests, it was officially opened on November 9, 1989, resulting in the reunification of East and West Germany the following year.