The geography of the past is studded with walled cities. Jerusalem and Rome, to name but two from antiquity, fortified themselves against enemies without. Later, in medieval times, the citizens of London and Paris built and rebuilt ramparts to safeguard their liberties, ones that many of their rural contemporaries, burdened with the feudal status of serf, were denied. Only in the 20th century has a city had a wall rammed through its innards, circumscribing the freedom of two-thirds of its people, forcing upon them a serf-like tie to the land. Only in Berlin.
Images of the violation recur. When Berliners in...