Whoever gets to design the real, 80,000-seat Olympic stadium at Stratford will know they can't do nearly so well, or not for the money that will be available. The Wembley architects, Lord Foster and HOK Sport, have done the landmark thing so well that the options for serious aesthetic rivalry are extremely limited. And then there's the Greeks. Assuming the main stadium for this year's Games is finished in the nick of time as everyone including its architect Santiago Calatrava assures us it will - well, that's a good-looking place as well. Calatrava is famous for designing sculpturally bony bridges, and his stadium roof structure in Athens is really just two big parallel bridges like that. Foster and HOK's Wembley plays a similar game to different effect: in our case the big arch is effectively a single suspension bridge. However, if London were to win the Olympics after next - which means beating off Madrid, Moscow, New York and Paris - unfortunately we have the hardest act of all to follow, and it's neither Wembley nor Athens. It's the Beijing stadium of 2008. And that one is a corker.

Beijing's is a design by Swiss architects Herzog and de Meuron, responsible for the conversion of the old Bankside power station into Tate Modern in London and the Stirling Prize-winning Laban Centre down in Deptford. These days they are global superstars, trotting round the world producing an icon here, a landmark there. In the process of becoming famous they seem to have abandoned their Calvinist leanings towards austere boxes, and gone all expressionist. Their stadium is a great overblown birds' nest of a thing, the kind of overwrought structure that has design engineers weeping into their beer at the sheer profligacy of it. But, as with many an overwrought structure from Chartres Cathedral to the Sydney Opera House, it looks just gorgeous. If it is built anything like it has been imagined, then Beijing's Olympics will be forever remembered. And London has to follow that. Well, it can't, except in the strictly chronological sense. They'll be wanting to get some serious architectural iconographers in. But given that there is no way we can spend like the Chinese, it might be a better bet to admit defeat on the icon front and go all low-budget and functionalist instead.

Politics will always intrude, of course. Unfortunately we do not remember the Munich Olympics of 1972 for their marvellous translucent cable-net roofs by Frei Otto and Gunter Behnisch. We remember the bloody Arab-Israeli terrorist incidents that marked the occasion. As for Werner March's undeniably splendid stadium in Berlin for the 1936 Olympics, still in existence, that will be forever associated with Hitlerian pageantry and pique.