Ai Weiwei, "Forge"

The Chinese artist and activist occupies both of this gallery's locations, in Chelsea and on Fifth Avenue, with new works. Downtown, the highlight is an installation made of twisted steel rebar salvaged from schools in Sichuan, China, that collapsed during the May 2008 earthquake due to shoddy construction (a fact covered up by the Chinese government). The space uptown, meanwhile, presents an installation of 2,500 porcelain crabs, a reference to a rally the artist held to protest the government's demolition of his Shanghai studio (supporters were treated to a feast of 10,000 crabs).