Berlin Wall Fast Facts

West Berliners crowd in front of the Berlin Wall on November 11, 1989, as they watch East German border guards demolishing a section of the wall in order to open a new crossing point between East and West Berlin.

(CNN)Here's some background information about the Berlin Wall, which enclosed West Berlin from 1961 to 1989, in an attempt to prevent East Berliners from fleeing to the West. It became a symbol of East/West relations during the Cold War.

The Wall:
The Berlin Wall began as a temporary border of barbed wire fencing and evolved into a fortified concrete barrier with armed East German border guards.
    The wall between East and West Berlin was nearly 12 feet high and approximately 27 miles long, containing 302 guard towers and 55,000 anti-personnel explosive devices (landmines).
    To prevent attempts to scale the wall, or escape by digging underneath, the wall was reinforced with wires, mines, pipes, trenches and wire-mesh fencing.
    A wide-open area of dirt and sand, a buffer zone between the two walls, became known as "no man's land" or the "death strip," where guards in more than 300 watch towers could shoot anyone trying to escape.
    The most famous border crossing was known as Checkpoint Charlie.
    Timeline:
    February 4-11, 1945 -
    In the face of Germany's defeat in World War II, the Allies' Yalta Conference agrees to divide Germany into four zones of occupation: Great Britain, France and the United States occupy the western and southern portions, and the Soviet Union occupies the eastern. Berlin, located in Soviet territory, is also divided into east and west zones.
    1949 - The western and southern zones occupied by Britain, France and the United States become West Germany (The Federal Republic of Germany). The Soviet zone becomes the German Democratic Republic (GDR), or East Germany. West Germany is a democratic republic. East Germany is a communist country aligned with the Soviet Union.
    1949-1961 - More than two million East Germans escape to the West. Foreign citizens, West Germans, West Berliners and Allied military personnel are permitted to enter East Berlin, but East Berliners need a special pass to leave.
    August 12, 1961 - East German Communist Party leader Walter Ulbricht signs the order for a barricade separating East and West Berlin.
    August 13, 1961 - East German security forces chief Erich Honecker orders police and troops to erect a barbed wire fence and began construction of concrete barricades.
    August 18, 1961 - US Vice President Lyndon B. Johnson and retired General Lucius Clay fly to Berlin as a show of US support for West Germany.
    August 21, 1961 - Approximately 1,500 US troops arrive in West Berlin.
    August 23, 1961 - West Berliners without permits are banned from entering East Berlin.
    June 26, 1963 - US President John F. Kennedy speaks to an enthusiastic crowd at West Berlin's old Schoeneberg Rathaus (city hall): "Today in the world of freedom the proudest boast is 'Ich bin ein Berliner' ('I am a Berliner') all free men, wherever they may live, are citizens of Berlin. And therefore, as a free man, I take pride in the words 'Ich bin ein Berliner.'"
    September 12-13, 1964 - The Rev. Martin Luther King Jr. visits Berlin at the invitation of West Berlin Mayor Willy Brandt. King delivers a sermon on both sides of the wall titled "East or West -- God's Children".
    September 1971 - An agreement is reached allowing West Berlin and East Berlin to import and export goods.
    December 1972 - West and East Germany sign a treaty normalizing diplomatic relations and recognizing each other's sovereignty.
    June 12, 1987 - In a speech at the Brandenburg Gate, US President Ronald Reagan challenges Soviet General Secretary of the Communist Party Mikhail Gorbachev, leader of the USSR, to "tear down this wall!"
    April 3, 1989 - GDR border guards are instructed to stop "using firearms to prevent border violations."
    October 18, 1989 - Communist Party chief Erich Honecker is ousted and is replaced by Egon Krenz.
    November 1, 1989 - More than a half million people participate in a pro-freedom rally in East Berlin, demanding free elections.
    November 2, 1989 - Egon Krenz announces sweeping political and economic reforms.
    November 6, 1989 - A preliminary law is passed that gives all citizens travel and emigration rights.
    November 7, 1989 - The East German cabinet resigns. Almost half of the members of the Politburo are removed and replaced the next day.
    November 9, 1989 - East Germany lifts travel restrictions to the West. Politburo member Guenter Schabowski announces that East German citizens can "leave the country through East German border crossing points," effective immediately.
    November 9-10, 1989 - Jubilant crowds tear down the wall piece by piece using their hands, pickaxes, sledgehammers and shovels.
    November 10-11, 1989 - Several new crossing points are opened, and tens of thousands of people cross over into West Berlin.
    October 3, 1990 - East and West Germany officially become reunified under the name the Federal Republic of Germany.