Some remain great cities, but they shouldn't stand still. They should move in the direction of a knowledge-oriented society. Most cities have to do something to draw attention to themselves and make their particular assets visible on the international radar. I'm not talking about developing countries, but about the United States and Europe.

Hamburg will have a new and important attraction with which it can distinguish itself from other cities. But the important thing is that activities should not just be limited to the building, but that the concert hall should symbolize a general mood of creative rejuvenation.

Contradictions, most of all, a balance between chaos and order. It needs neighborhoods vibrating with energy just as much as cozy little corners and parks; well-tended, middle-class sections as well as an alternative scene; technology centers for innovative youth and social facilities for older people.

City needs creativity to retain the high performers who have lived there for years as well as to attract new, interesting residents.

Detroit is an urban hell. But even in this city of the dying auto industry, there is reason to hope, if they manage to combine the creative forces of designers and other intellectual "suppliers" in other ways.

As far as population size goes, big is no longer important, and it can even be a drawback. In fact, the future belongs more to second-tier cities. Any place can become a world-class center today by finding an area in which it outperforms others, by thinking for the long term, by expanding its competitive abilities and by operating globally.

Hamburg is getting a new symbol with its new Elbe Philharmonic concert hall. Such an architecturally impressive building is built somewhere in the world maybe once every five years, if you're lucky.