'Century City' offers a host of unfamiliar sensations. We might ponder the similarity between avant-gardist Aleksandr Rodchenko's Spatial Construction 13 and the form of the Stalinist Ministry for Foreign Affairs in Moscow; puzzle over the inclusion of family snapshots in the section on Lagos; pore over the chewing gum which Hannah Wilke has moulded into the shape of female genitalia, or conclude that Ludwig Wittgenstein designed the house for his sister in 1928 to dampen Vienna's rampant sexuality. Let the imagination go, in other words, and you might have fun - after all, when Tracey Emin and Brian Sewell agree on something, as they do about this exhibition, it licenses some perversity.
'Century City' is a sequence of separately curated displays on different cities during different periods of the last century. Each is represented by various media, from architecture and painting to fashion, film and video.
It is another in that genre of exhibitions about cities which includes Rem Koolhaas' 'Cities on the Move', and several lamentable events at the RIBA which confirm the difficulty of rendering such complex material into an exhibition. It is certainly fraught territory, and guidance from Lewis Mumford might not have gone amiss.
Any such compilation courts controversy, though, and to quibble about the exact periods of Paris 1905-15, Vienna 1908-18, Moscow 1916-30, Rio de Janeiro 1950-64, Lagos 1955-70, New York 1969-74, Tokyo 1967-73, Bombay/Mumbai 1992-2001 and London 1990-2001 is as otiose as to question the choice. They were all major centres of creativity at these times.
But the nagging question of 'why these cities at these periods?' is intensified by some of the curatorial decisions. As the sole plan in the whole exhibition - of Lagos - says so much about an unfamiliar city, I wanted more. It is also striking that the Vienna section has no mention of Robert Musil's great novel, The Man Without Qualities - surely the best evocation of Viennese psychology in the Habsburg's twilight, and no less outside the specified time than the Stonborough Wittgenstein House of 1928-30.
When the individual sections lack a compelling coherence these questions become legitimate, and more follow. Why are so many of the curators non-residents of the cities themselves? Lutz Becker is based in London, not Moscow. Okwui Enwezor and Olu Oguibe live in Chicago and New York, not Lagos, Reiki Tomii in New York rather than Tokyo. Of course, residency is not essential for successful curation, but it suggests that familiarity with the international curatorial circuit counts for more than familiarity with the city. If this were not Tate Modern's opening shot in the raging war of urban studies, it would be very tempting to give up and go to the permanent collections.
Then, suddenly, in a blazing shaft of light, all these questions resolve themselves. It comes in the section on London.Why 19902001? Hints throughout the exhibition have pointed out the interactions with 'dictatorships' and the chosen periods - the election and fall of Nixon; the generals in Brazil; the fallout from Biafra in Nigeria. 1990, one recalls, is the year the grey pre-dawn of Major replaced the dark night of Thatcherism. Then London emerged from its cultural slumber through the agency, of course, of the Tate - an institution whose popularity is enough in Blairite Britain to give it real authority.
The artists represented are, on the whole, those whom the Tate has already promoted.
The implication here is that the Tate offers the key to understanding urban culture, just as MOMA's early curatorial policies depended on its belief that it held the secret to modern art, and therefore the whole of artistic tradition. The Tate has already declared its position as a player on the urban scene - remember the competition-winning scheme which 'integrated' the power station with the Southwark hinterland? This exhibition is a further step towards the idea, so eloquently encapsulated by the Guggenheim hype, that art galleries brand their cities.
MOMA found an unlikely ally in the CIA to promote its view of art. The Tate, perhaps, looks higher. At the entrance to London a 'timeline' highlights events such as the removal of hereditary peers from the House of Lords, Livingstone's candidature and mayoralty, the Macpherson Report, the BSE cull and the Race Relations Bill, which have helped Britain towards the high noon of Blairism. I wonder whether those politicians here identified as part of London's cultural renaissance have given money to the gallery. In these days of passports and Hindujas, I think we should be told.
Such are the inevitable flights of fantasy that this exhibition, facile in conception, flawed in execution and flaccid in installation, is likely to provoke. Had each - or indeed any - of the different sections been sufficiently captivating, such thoughts would not occur. But they do little to provoke serious discussion or insight. It is an exhibition devised, it would seem, to make zombies of its visitors, monkeys of its curators - and gods of its progenitors.
Jeremy Melvin is a writer and teacher