The communist East German government completed construction of the Berlin Wall on this date back in 1961. Everyone's seen photos of segments of the concrete wall spray painted with graffiti, and other photos of refugees running through barbed wire to escape East Germany. But I'd always wondered what the Berlin Wall looked like in its entirety.
The term 'wall' always implied to me a straight line running between East Berlin and West Berlin. But Berlin itself was deep inside East Germany. So while a wall like that might keep East Berliners from emigrating to West Berlin, it wouldn't keep out other East Germans. HERE's a map of the wall which answers that question: the Berlin Wall was a full circle that turned West Berlin into a sort of fortified castle.