It's everything else - especially the tourist-infested river side of the building - that's the problem. It is a true memorial to the free-market ideology of Margaret Thatcher when she kicked out the troublesome old Greater London Council in 1986: let the market decide. Seven years later, the building was sold to a Japanese company, Shirayama Shokusan, which then divvied the place up between anyone who was prepared to pay the rent. Plus one or two rent-free bits, such as the suite of rooms at one end occupied by the Princess Diana Memorial Fund. This certainly prevented the vast building complex from becoming an empty, decaying burden to the State - though of course years later a new City Hall by Norman Foster had to be built downriver, at public expense, for a new London authority which is already short of space there: plus ca change. The upshot of all this, back at the old place, is an experience in dislocation. What is this building, exactly? What's it for?

It could have had a different future. It's clear that the building lends itself to an art gallery or arts institution use, even if it is full of bits, like the original marbled and paneled committee rooms and debating chamber, that the preservationists won't let you remove but which Saatchi has now deftly colonised. It could have been a different kind of Tate Modern. Years ago, it could have solved the expansion problems of the neighbouring South Bank cultural centre, which are still not resolved: everything from a small concert hall to a new film centre could have gone in there. The nearby Young Vic is having to rebuild its time-expired theatre: other theatres are planned in the vicinity. County Hall could have given a sheltering roof to them all.

But even assuming the high-culture route was for some reason closed, County Hall could still have been much more. It could have easily housed one of London's expanding universities, much as the old Royal Naval College in Greenwich is now part of the university of Greenwich. With Kings College London nearby, you would not have to look far to find a suitable tenant. Or the Royal College of Art in Kensington, currently going through planning hell with the expansion plans for its landlocked site, could have had all the space it needed.