What a skyscraper should be is a lot more than a vertically extruded tube of offices, of the Canary Wharf variety. But this is exactly what most of the towers proposed today are, even though some are better designed than others. The financial centre of the City of London - which rejected towers in favour of huge "groundscrapers" in the 1980s - has now reversed that view and declared that, once again, tall is good. But the City cares little for aesthetics or convivial urban living. All it ever wants, towards the top of every economic cycle, is lots of new office floorspace - whatever shape it takes. This is because it is paranoid about big financial institutions upping sticks and going to Frankfurt instead, so diluting all its service-industry power. But if you ignore the City and its new friend Ken Livingstone, the London mayor, more interesting possibilities open up.
The most worthwhile skyscrapers in the world are those that mix up their uses - that contain homes as well as offices, shops, cafes, gardens and and health clubs, even hotels. These buildings are now commonplace in the Pacific Rim and America, rare in greater Europe, and non-existent in Britain. The 1,000 - foot tower proposed for London Bridge Station by developer Irvine Sellar and architect Renzo Piano - which if built, would be Europe's tallest - shows signs of being such a mixed-use skyscraper, though details are still maddeningly vague. Lord (Norman) Foster has designed several such towers, even one in the City of London - but that was deemed too tall, so it was rejected. Still unbuilt is his original "Millennium Tower" for Japan, intended to be the world's tallest and a veritable city in itself.
It's not a new idea. The town-tower is originally a 1950s dream. The brilliant American architect Frank Lloyd Wright designed a complete 100,000 inhabitant, 500-storey city-in-a-tower, which he dubbed the "Mile High" as long ago as 1956. It was saucily speculative. But as Wright sagely observed: "No-one can afford to build it now - but in the future, no-one can afford not to build it."
Such a tower may, eventually, be built in Britain. But in London? I doubt it, despite the promise shown by the London Bridge example, despite the fact that Renzo Piano is one of the world's great architects, despite the fact that a huge public transport interchange is the logical place for such a tower - which would thus create little traffic congestion. But no: it would be visible from Hampstead, after all. It has already been reduced in height once: my bet is that it will get smaller still, and that as it shrinks the proportion of offices in it will grow.
But there's a better location, which might please even the Hampstead set - the Dome site on the Greenwich peninsula. There, all round the Dome, a forest of slender residential towers is proposed by David Marks and Julia Barfield, architects of the London Eye observation wheel. But maybe that's not enough. Maybe the Dome site is exactly where London's one and only true multipurpose, world-class town-tower should really go. But don't hold your breath. London is London. It likes to sprawl, it doesn't really like reaching for the sky. Birmingham and Manchester, Liverpool and Glasgow: here's your chance.
