While you can trace any number of Western influences in his work - his careful ordering and laying-out of Neolithic axe-heads, collected over a decade, is reminiscent of Richard Long, his iconoclastic destruction-pieces recall Cornelia Parker, his large sculpture made from conjoined bicycles returns to Duchamp - he has also developed a clear voice of his own. He seems energized by being in China at this time of all times, when it is changing so very rapidly.

The story with Herzog and de Meuron is twofold. On the one hand, when they were invited to participate in the competition for the stadium, they wanted advisors on several aspects of Chinese culture, to ensure that their design gave out the right messages. And on the other hand, they routinely work with artists on their building, as they did with Michael Craig-Martin on the Stirling Prize-winning Laban Centre in Deptford. So they wanted one of their advisors to be a Chinese artist who might share some of the slightly tangential, somewhat irreverent and lateral-thinking, H & de M approach to a stadium that they describe as "a large collective vessel…of an almost archaic immediacy." Given that Ai Weiwei's take on art is to stimulate doubt and questioning, it would seem to be an ideal match.

The match-making was done by Uli Sigg, former Swiss ambassador to China and a keen collector of Chinese contemporary art. H & de M signed up Sigg to be their "expert advisor for logistics and specific Chinese conventions". He knew Ai Weiwei and introduced him to them. Thus the partnership was born.

"It's a dialogue that starts early in the design process. That is what the office is interested in," says a practice spokesman. "Living in China, he knows how people respond to certain forms and symbols. His input is important. He is almost part of the team."

Ai Weiwei's position is an interesting one. He is the outsider who is not outside, the challenger who is tolerated and respected by the regime, who fuses Western and oriental attitudes to culture. Many large-scale building projects are heading for completion in Beijing in time for the Olympics in 2008. All are interesting in different ways. But the stadium, you may be sure, will have an extra resonance because of his involvement.