Ai Weiwei is a Chinese contemporary artist, active in sculpture, installation, architecture, curating, photography, film, and social, political and cultural criticism. Ai collaborated with Swiss architects Herzog & de Meuron as the artistic consultant on the Beijing National Stadium for the 2008 Olympics. As a political activist, he has been highly and openly critical of the Chinese Government's stance on democracy and human rights. He has investigated government corruption and cover-ups, in particular the Sichuan schools corruption scandal following the collapse of so-called "tofu-skin schools" in the 2008 Sichuan earthquake. In 2011, following his arrest at Beijing airport on 3 April, he was held for over two months without any official charges being filed; officials alluded to their allegations of "economic crimes" (tax evasion). In October 2011 ArtReview magazine named Ai number one in their annual Power 100 list.