Last month, 10 years on from the fall of the Wall, Germany officially inaugurated its new (and old) parliament, the Reichstag. Sir Norman Foster's light and airy building - which first ventured back into the limelight when it was wrapped by the artist Christo in 1995, just before the builders moved in - is to be the new symbol of German democracy. By preserving some of the Russian victors' graffiti from 1945, uncovered during construction works, Foster's building seeks to confront the ghosts of the past, and to imply the hidden continuity in Berlin's history.
Elsewhere, however, the continuity has been broken. As so often before, Berlin has set out to create a blank slate. It is unclear if it can succeed. In the words of Simon Norfolk, who took the photographs on these pages, "memory is obstinate".
Memories of the Wall may prove especially obstinate. It had always been famously surreal, of course, enclosing the little island of West Berlin, a living museum of brash capitalism in the midst of a grey Communist sea. In the city centre, on either side of the Wall, there was a large area of no-man's land - most famously, the deadly emptiness of Potsdamer Platz, the once- and-future Piccadilly Circus of Berlin, with its minefields and desolation. Parts of the overhead railway in East Berlin ran right along the mined border itself; East Berliners in the railway carriages always looked the other way.
But the points of urban contact were in some respects less startling than the Wall around the city's fringe. To the north, west and southern edges of West Berlin, where the wall sliced through suburbs or countryside, the very banality became unsettling and bizarre. From a first-floor window, you could observe the two worlds simultaneously. Here, a Western line of washing; there, an Eastern line of washing. Here, an East Berlin child on a bicycle; there, a West Berlin child on a bicycle. Nothing between them but the question: which street were their parents living on, on 13 August 1961, the day the Wall went up? That geographical accident determined everything that followed, for more than a quarter of a century.
Other East European countries paved the way for the collapse of the Wall and then of East Germany. By April 1989, the Polish Communists had been forced to agree to elections in which the Solidarity opposition would roundly defeat them. Then, on 2 May 1989, 10 years ago tomorrow, the Hungarians snipped a hole in their border fence, the literal Iron Curtain. It was little more than a photo-opportunity, intended to demonstrate the new Hungarian openness - the Hungarian reformers had promised multi-party elections for the following year. But it soon became the entry point to the West for a flood of East German refugees. That, in turn, put unprecedented pressures on East Germany itself.
Finally, on 9 November 1989, amidst a mixture of chaos and predictability, the Wall cracked open. The show was over. Within months, German unity was agreed. The souvenir-hunters soon arrived on the scene - chipping away with little hammers, eagerly pocketing the small lumps of demystified evil. The souvenir-hunters were then followed by the bulldozers, getting rid of the Wall altogether. The Wall was bad; the Wall should go. Theoretically, it was logical enough. But the disappearance of this ominous landmark created a new oddity - a void that nobody quite knew how to fill.
When German unification came, less than 12 months after the fall of the Wall, the pretence was that Berlin would once again be a single city, and that the city could return to a comfortable status quo ante. Willy Brandt, Germany's most respected post-war leader, famously declared: "What belongs together is coming together." In his philosophical intent, he was right. A split Germany was a nonsense. But the two worlds had grown more separate during the intervening decades than either side was at first ready to admit.
The "Wall in the heads", as it soon came to be known, was increasingly impregnable, even as the last debris of the concrete Wall was carted off to the crusher's yard. West and East Berliners began to speak of each other in mistrustful or contemptuous tones. The once-menacing border - 155km, 22 bunkers, 300 watchtowers - became just a line in the asphalt or the fields. But West and East Berliners alike continued mentally to carry a foreign passport when visiting "the other side".
In a few places, fragments of the Wall have been preserved - for example at the East Side Gallery, an uninspired peace-and-love art display that is popular on tour-bus itineraries. Mostly, however, the scar is almost invisible - betrayed only by a different shaped set of cobblestones, a different shade of paint, or a freshly planted stand of trees. Today's Berlin maps do not acknowledge that the Wall ever existed. The curious visitor must thus carry two maps - an old map to locate the Wall, a new map to find what Yet-Another-Communist-Hero Street is now called. (The old West and East Berlin maps were themselves quite differently presented: the West Berlin maps pretended that Berlin was still a single city, which just happened to have a thick red line cutting through its important streets; the maps of "Berlin, capital of the German Democratic Republic" treated West Berlin as a great white space, an irrelevant terra incognita.) It is now almost impossible to work out where the most important dividing line in Europe ran, just 10 years ago. Even in areas of Berlin that I thought I knew well, I have found myself stepping gingerly back and forth across the former "death zone", in vain attempting to locate the line in the tarmac that once separated two worlds.
This political hopscotch is not a game that Berliners themselves often play. Most are keen to pretend that everything today is completely normal, without pressing memory buttons from the past. Few admit to feeling any kind of frisson in crossing what was once such a lethally important line. Occasionally, there is a touch of post-modern irony - an East German watchtower, for example, finds itself marooned in the courtyard of newly built apartments, left high and dry by the outgoing tide of history. More commonly, remnants of the old world are discreetly incorporated into the modern urban landscape. The Hinterlandmauer or "hinterland wall" - a secondary stage of impregnability that would-be escapers had to break through - now looks like just another urban boundary wall, with no hint of its threatening history.
And yet, even monsters deserve a decent burial if the ghosts are not to return. For decades after the Second World War, Germany failed fully to address the Nazi past, seeking instead to treat Stunde Null, the Zero Hour of 1945, as an opportunity to pretend that the past was not just another country, but was no country at all. Until a few years ago, it was almost impossible to locate sites that had played a key role in the Hitler era. Now, there is a new opening-up which labels the important architectural sites of the Third Reich. The Berlin Wall has not been granted the same honour.
As architectural historian Brian Ladd argues in his book Ghosts of Berlin, this is a city "whose buildings, ruins and voids groan under the burden of painful memories". That is as true of the Berlin Wall as it was of the city's many Nazi sites. One day, the two Berlins will indeed come together. But their apartness must be recognised, for a lasting reconciliation to become real. Otherwise, the silent spaces may prove dangerously vocal in years to come. The mines between West and East have been cleared; the psychological minefields remain