From Wikipedia

The Road To The Wall

The Berlin Wall (German: Berliner Mauer) was a physical barrier erected by the German Democratic Republic (GDR) (East Germany) completely encircling West Berlin, separating it from East Germany, including East Berlin. The longer inner German border demarcated the border between East and West Germany. Both borders came to symbolize the Iron Curtain between Western Europe and the Eastern Bloc.

Prior to the Wall's erection, 3.5 million East Germans had avoided Eastern Bloc emigration restrictions to escape into West Germany, many over the border between East and West Berlin. During its existence from 1961 to 1989, the Wall stopped most such emigration and separated East Germany from West Germany for more than a quarter of a century. The Wall included guard towers lining large concrete walls circumscribing a wide area (later known as the "death strip") containing anti-vehicle trenches, "fakir beds" and other defenses. After its erection, around 5,000 people attempted to escape circumventing the wall, with figures of the resulting death toll varying between 98 and 200.