And this pop star, who has come to the scene of his childhood dreams in order to turn them into reality, who has moved to the capital of the very Weimar Republic that his native England increasingly resembled - this David Bowie comes down to earth in Berlin with a jolt. He suddenly finds himself surrounded by young people of his own age whose fathers really were in the SS, he says later. And that helped to wake him up. At the Wall, Bowie found his own name among the graffiti - the last two letters formed a swastika. He was not best pleased.

In the shadow of this graffiti-covered Wall, Bowie wrote his most celebrated Berlin song, Heroes. It concerns a pair of lovers who meet every day under the noses of the East German border police. Bowie sings: "I, I can remember / Standing, by the Wall / And the guns shot above our heads / And we kissed as though nothing could fall / And the shame was on the other side/ Oh we can beat them for ever and ever / Then we could be Heroes just for one day." No other pop song about the Wall comes near it. When President Kennedy came to West Berlin in June 1963, he bequeathed to the city four words: "Ich bin ein Berliner." Bowie bequeaths his temporary home this song - and its sentiments are exactly the same. Sometime in 1978, however, he is off again. Healed and chilled out, he moves on to New York.

One more time, though, he is able to feel like a Berliner. On 6 June 1987, David Bowie performs in front of the Reichstag, next to the Wall. Before an audience of 70,000, he reads out a message in German: "We send our best wishes to all our friends who are on the other side of the Wall." Then he sings Heroes. On the other side of the Wall, as near as possible to the Reichstag, hundreds of young East Berliners strain to hear echoes of the concert. They listen as Bowie greets them. And they listen to his song. Their song. Many of them charge towards the Brandenburg Gate. Troops and police bar their way. Stones and empty beer cans are thrown. Over the next two evenings, when the Eurythmics and finally Genesis give their "Concert for Berlin", the crowds in East Berlin grows bigger and the riots become more violent. In their internal reports, the Stasi record the deteriorating situation night after night: human chains are formed, in total "158 persons detained. They are mainly young adults born between 1964 and 1969. 25 young women were detained. Some of their behaviour was aggressive." And then the Stasi report states: "Loud whistling and chanting (including for the first time ‘Down with the Wall') in response to police actions." The West Berlin tabloid press reports that the chanting had already been heard - on the evening when Bowie performs Heroes.