"I promised the Senate that I would be in Berlin until the museum opened," he recalls. "Little did I know what that would mean. Still, until September I am keeping my promise. And of course I like Berlin a lot. It’s such an interesting city. And it’s been an interesting time, going through all the cataclysms and transformations that followed the fall of the Wall. It’s been an incredible journey, an adventure. Who could ever have predicted these things?"

I’d bet on him staying there, even though he now has projects all around the world and could live anywhere he chose. And this not just because he now has a large office of around 40 people in Berlin. It’s clear that the place retains its fascination for him, 15 years after he designed a famous theoretical scheme, the "City Edge Project" which - far from attempting to heal the scars of the city as was then fashionable - exploited to the full the weird east-west disjunction caused by the Wall and its minefields. City Edge responded in kind, surgically slicing through the surviving urban grain. It was lumped in with Deconstruction, the exploding and splintering of conventional shapes - but it was curiously appropriate for divided Berlin. Without the fertile ideas of City Edge, there could have been no Jewish Museum. And without that - who knows? - Danny might never have built anything much.

Nothing since has caused his interest in Berlin to waver. "It’s an extraordinary city with fascinating people. It’s still a city that is three-quarters imagination and one quarter reality," he says. "It’s still all about dreams. And even although large areas have been rebuilt, it’s still only a fragment of what we know of Berlin. I think today people look with hope at what might happen."

But in truth Libeskind’s architecture is not very Berlin, or in other words is very un-Prussian. In Berlin, they like the old idea of big, relatively low, rectangular buildings that stick to the line of the streets and have courtyards at their centres - very like Danny’s own working environment, in fact. Legions of the world’s best architects have come to Berlin with big ideas and retired bruised, forced by the ultra-strict city planners to pour their creativity into the old 19th century mould. Libeskind was given special dispensation to ignore all that. He was lucky to be one of the first on the scene, well ensconced by the time the redevelopment floodgates opened and the planning guidelines drawn up. And it helped that the Jewish Museum - which began life as a mere extension to the existing Berlin Museum - was outside the historic centre, in an inner, slightly shabby, residential suburb. He got away with it. His building was so completely unlike anything the city had ever experienced, that it seemed mesmerised by it. They even allowed his jagged building to project into the street, and the Berlin planners never let that happen.

By then, he was a definite architectural type, the mature wunderkind. Libeskind was born in Lodz, Poland, in 1946, which made him 43 when he won the Jewish Museum competition. In Western architecture, you are a baby if you are under 40, you don’t do your best work until you are over 50, and if you are seriously good you then just go on getting busier and busier until you drop dead at your drawing-board in your eighties or even nineties. It’s the way of architecture. It’s difficult, it takes time to master, it takes time to make a name, it takes time to get anything built. Especially if, like Libeskind, you are reinventing the rules of the game. So Danny is now 55. You’d expect him to be approaching his peak, and he is. You’d hope that he’d be busy, and he is. Very. But it has all been comparatively recent. It has all happened in the last decade, and most of it has happened in the last two or three years. Danny finds himself in the strange position of being bankable.