The Inner German Border, AKA the Iron Curtain.
I remember those days too. We used to take groups from our base to go on patrol with the British Frontier Service. Between stops we would swap rank tabs, hats and jackets just to wind the other side up when they took our picture.
What an obscenity that border was! Villages cut in half, mines and anti-personnel measures (only on their side I might add) but badger gates to let the wild life through. The border wasted an area of land equivalent to Luxembourg and Denmark combined.
Do you remember the big open cast brown coal mine near Helmstedt? When the border went in the machinery was up the east end so they took it and used it to mine coal that they then sold back to the west.