After World War II, Berlin was divided into four sectors. The Soviet Union, the USA, the United Kingdom and France each had a portion of the city under their control. The Soviet sector was by far the largest and covered most of eastern Berlin -- Friedrichshain, Köpenick, Lichtenberg, Mitte, Pankow, Prenzlauer Berg, Treptow, and Weißensee.
From 1949 the three sectors controlled by the United States, Britain and France (West Berlin), although nominally independent, were in effect a part of West Germany that was completely surrounded by East Germany.
Initially the citizens of Berlin were allowed to freely move between all the sectors, but as the Cold War developed movement became restricted; the border between East and West Germany was closed in 1952 and the attractiveness of the Western sectors of Berlin to the citizens of East Germany increased. Around 2.5 million East Germans crossed into the West between 1949 and 1961.
To stop the migration, construction of a wall around the three western sectors began on August 13, 1961, East Berlin. It first consisted of barbed wire, which was later replaced by the actual wall. The wall physically divided the city; as it completely surrounded West Berlin, it effectively turned the western sectors into an island in the eastern territories.
East Germany claimed that it was an "antifascist wall of protection" intended to avoid aggression from the West. It was clear from the beginning that this justification served as a cover for the fact that the citizens of East Germany had to be prevented from entering West Berlin and thereby West Germany (East Germany did not completely control traffic between West Berlin and the rest of West Germany).
The Wall was over 155 km long. After the initial construction, it was regularly improved. The "fourth generation wall", begun in 1975, was reinforced concrete, 3.6m high and constructed out of 45,000 separate 1.5m sections at a cost of 16,155,000 East German Marks. The border was also guarded by mesh fencing, signal fencing, anti-vehicle trenches, barbed wire, over 300 watch towers, and thirty bunkers.
At first, there was only one crossing point for Westerners, at Friedrichstraße; the Western powers had two further checkpoints, at Helmstedt on the border between East-Germany and the main part of West-Germany and Dreilinden on the south border of West Berlin. The checkpoints were named phonetically Alpha (Helmstedt), Bravo (Dreilinden), and Charlie (Friedrichstraße) (see map of Berlin with crossings).
During the Wall's existence there were around 5,000 successful 'escapes' into West Berlin; 192 people were killed trying to cross and around 200 were seriously injured.
On August 23, 1989, Hungary removed its border restrictions with Austria and in September 1989 more than 13,000 East Germans escaped via Hungary. Mass demonstrations against the government in East Germany began in the fall of 1989. Erich Honecker resigned on October 18, 1989, and he was replaced by a short-lived successor Egon Krenz a few days later.
The travel restrictions for East Germans were somewhat lifted by the new government on November 9, 1989. After a misunderstanding, Günter Schabowski announced in a press conference that all restrictions had been abandoned, and tens of thousands of people immediately went to the Wall where the border guards opened access points and allowed them through. November 9 is thus considered the date when the Wall fell.
On Christmas Day, December 25, 1989 Leonard Bernstein gave a concert in Berlin celebrating the end of the Wall, including Beethoven's 9th symphony with the chorus' word "Joy" changed to "Freedom". Roger Waters performed the Pink Floyd concept The Wall in Potsdamer Platz on 21 July 1990, with guest including The Scorpions, Bryan Adams, and Van Morrison.
Some believe November 9 would have made a good German National Holiday, since November 9 is also the date of the declaration of the Republic in 1918 and of the so-called Kristallnacht in 1938, thus giving a good profile of the good and evil in German history. Instead, October 3 was chosen.
The fall of the wall considerably changed traffic patterns in the city, and the M-Bahn, a maglev system connecting 3 metro stations over 1.6 km, was deconstructed just months after its official opening in July 1991.