On Monday, an outdoor art installation by Chinese artist-activist Ai Weiwei will open in New York, but the whereabouts of their creator remain unknown. Ai was taken into custody by Chinese authorities on April 3.

The artist behind Beijing's Olympic Stadium is now in government custody and artists all over the world are planning protests in support of his release. NPR's Laura Sydell spoke with the controversial artist in 2008. Even then, he was pushing boundaries.

Chinese authorities detained China's most famous artist at the airport on Sunday as he was trying to leave the country. Ai Weiwei, who designed the iconic Bird's Nest stadium built for the Beijing Olympics, has been a frequent critic of the government.