Here's a look at what you need to know about the Berlin Wall, seen as a symbol of the Cold War and East/West relations. The Wall stood from 1961 to 1989, separating democratic West Berlin, in West Germany, from Communist-controlled East Berlin and from the rest of East Germany.
The Wall: The Berlin Wall evolved from a temporary border of barbed wire fencing to a heavily fortified, concrete barrier with numerous guards, tank traps, and other obstacles.
It encircled the city of West Berlin and stretched approximately 100 miles.
The wall between East and West Berlin was 11-13 feet high and stretched 28 miles.
Buildings behind the barriers were demolished, and the wide open area became known as "no man's land" or the "death strip," where guards in more than 300 sentry towers could shoot anyone trying to escape.
Wires and mines were buried underneath the surface to prevent escape attempts; pipes on top of the wall prevented it from being scaled.
Over 100,000 people attempt to escape over the wall. Between 5,000 and 10,000 succeeded.
Approximately 200 people were killed while trying to escape; many of them were shot by guards or had a fatal accident.
The most famous border crossing was known as Checkpoint Charlie.
Sections of the wall may be viewed at NATO Headquarters in Belgium, midtown Manhattan, and the Ronald Reagan Presidential Library.
Timeline: February 1945 - In the waning days of World War II, the Allies' Yalta Conference divides Germany into four zones of occupation: Great Britain, France and the U.S. occupy the western and southern half, and the Soviet Union occupies the eastern half. Berlin, located in Soviet territory, is also divided into zones.
1949 - The western and southern zones occupied by Britain, France, and the U.S. 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 allowed 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.
August 15, 1961 - The first concrete barrier is built.
August 18, 1961 - U.S. Vice President Lyndon B. Johnson and General Lucius D. Clay fly to Berlin as a show of U.S. support for West Germany.
August 21, 1961 - Approximately 1,500 U.S. troops arrive in West Berlin.
August 23, 1961 - West Berliners without permits are banned from entering East Berlin.
June 26, 1963 - 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 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, U.S. President Ronald Reagan challenges Soviet leader Mikhail Gorbachev to "tear down this wall!"
April 3, 1989 - 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.