It's one of the eternal mysteries of life: why would anyone want to stage the Olympic Games? The money makes your nose bleed. Sober estimates say that the Chinese spent £20 billion on infrastructure for the Games here in Beijing; others say £30 billion. That's not counting the money invested in sporting talent since they started bidding for the 2000 Games in 1993.

London will spend a mere £9.3 billion on infrastructure, and there has been enough whingeing about that. It's about what Athens paid four years ago. It's not cheap, so what do you get back? For a start you get the world going through your dirty laundry. Would we be so excited about Tibet, Darfur, democracy, human rights and the treatment of Falun Gongers if the Olympics didn't concentrate the mind?

And with all that investment, it can still backfire. It did at Atlanta in 1996. Why did Atlanta do it? Provincial chippiness - to show that anything the smug cities of the West and East could do, Georgia could do better. But the organisation was terrible, the attitude all wrong, the aggressive redneck security drove everybody nuts, and a bomb killed one and injured 100.

The smugness got to us. This was America and America was the tops, so you're lucky to be here, right? A colleague said that Athens should have got the Games: “Oh no. If the Games were coming to Georgia, they had to come to Atlanta.” In the end, the president of the International Olympic Committee, Juan Antonio Samaranch, refused to say that “these were the best Olympic Games ever”. It was a devastating judgment.

Why did Athens - the Greek one - want the Games? To show that Greece was bigger than anybody believed. For all our worldliness, most us base our views of foreign countries and cities on pretty basic notions and a simple archetype. Deep down, most of us have a slightly 'Allo 'Allo view of the world. The Olympics provide a brilliant, dangerous and expensive corrective.

Everybody knows that Greeks are mad, quarrelsome and chaotic, and couldn't organise a piss-up in an ouzo distillery. A country freshly inducted into the European Union had a point to make. The breathtaking nerve with building deadlines reinforced the stereotype: but the Games themselves were great. Not perfect: on the eve of the Games, two Greek athletes, including the national ikon, Kostas Kenteris, swerved a dope test, got rumbled and were kicked out. Also the Greeks themselves never turned up. They did what they always do in August and stayed on the islands.

But the Sydney Games of 2000 were an unqualified success. After seven years of devastating bitch-fight urban politics, the Games were a triumph. Most of the world had little idea that tucked away at the bottom of the planet was a thrilling vibrant, optimistic, cosmopolitan sorted-out, go-getting, can-do sort of place.

Barcelona had a simple succès fou: emerging from Madrid's shadow to prove that it was the real place, the sexy one. As Gary Lineker, then still a footballer, said after the opening ceremony: “Well Des, what do you expect from the city that gave us Miró, Dalí and Gaudí?” What indeed?

That is why you hold the Olympic Games: for the sake of matters impossible to quantify. It's billions spent on, er, good vibes. Oh, legacy is a part of it, and here, Barcelona is the template for what the Games can do for a city in terms of the hardware left behind. But it's in the software of vibes, good and bad, that the real legacy comes.

So where's it at with the Chinese? Since they decided to join the rough-and-tumble of international trade in the late 1970s, opening up has continued at ever-more-

dangerous speed. The Games are a coming-of-age ceremony, not in terms of culture - that happened several thousand years ago - but in terms of industry and urbanisation.

The Games show the world that China has arrived, and - perhaps just as important - they tell the Chinese the same thing. So far so good. But these things have their own momentum. The ambition of the young Chinese goes far beyond stadiums, subways and gold medals. China has been temporarily invaded by the world. The walls have come tumbling down. I don't think they can be built again.

China is an old society pregnant with a new one. Karl Marx said that in such cases the midwife was force: but the Olympic Games might play a part. So might money, trade, prosperity and the unstoppable forces of Westernisation, of which the Games themselves are a part. There is a possibility that, in staging the Olympics, the Chinese Government might be getting more than it bargained for.

And in four years' time, London. What's in it for us, apart from a Tube line, a stadium and the sexing-up of East London? The world will look at the British record in Iraq, our lapdog relationship with the US, question our policies on immigration, ask who we are to get tooty about human rights. Then the Games will begin and visitors will be aghast at the cost of hotels and taxis.

But the event will be fabulous - London is good at putting on a show - and the world will see that it is not just a place full of old buildings and crumbling imperial memories with a rather curious family in nominal charge. No, London will show itself and its nation as a cool place: ancient, yet up to the minute; with deep roots, bright new leaves. London will be the centre of the world for 17 days, bathed in the Olympic glow of fabulousness, for sport fascinates the world and blesses everything it touches. Best not bugger it up, then.

Simon Barnes's blog can be found at timesonline.co.uk/olympics

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