For 28 years from, 1961 to 1989, the Berlin Wall was the epitome - the defining image - of the cold war. I was in Berlin in December 1989, staying with friends and taking a cold chisel to part of the Wall on the outskirts. I knocked out a small chunk of concrete (the piece on the left of the photo) which brought down a rather larger slab of concrete. A Grepo (= Grenzpolizist, or East German border policeman) came running across No Man's Land, shouting at us to stop - not because we were breaking down the wall, but because he was worried we might hurt ourselves. I remember looking at his machine gun and thinking that six weeks earlier his orders would have been to shoot us. Instead, when he discovered I was from England, he said "It's a pity there is no graffiti on this part of the wall - here, you'd better have this piece." He handed me the piece of wall on the right of the photo.