In a city like London, the fact that cultures live together and cross-fertilize is a beautiful and natural thing. The many cultures in Amsterdam contribute to the city's high level of craziness - something which every interesting city should offer. But sometimes immigrants can live in parallel worlds which can exclude others and not be very attractive.

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.

The Germans are often too bureaucratic, too fixated on rules and not risk-oriented enough. And some of their officials have the feeling that they need to make everything in the cityscape look nice and pretty as quickly as possible. That was particularly apparent in the former East Germany after reunification. Then cities sometimes get a bit too neat and tidy.

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.

In a city like London, the fact that cultures live together and cross-fertilize is a beautiful and natural thing. The many cultures in Amsterdam contribute to the city's high level of craziness - something which every interesting city should offer. But sometimes immigrants can live in parallel worlds which can exclude others and not be very attractive.

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.