Ai WeiWei's retrospective at the Hirshhorn Museum proves an obligatory stop when visitors come to town. WeiWei's photography, large-scale installations and dissenting political commentary make "According to What?" one of the city's most intriguing exhibitions. "Forever Bicycles," a commentary on overpopulation, is probably my favorite piece in the show, so I was blown away when coming across photos of "Stacked" currently on display at Italy's Galleria Continua. Of the mesmerizing installation, MyModernMet says: "As the main mode of transportation in WeiWei's homeland of China, the installation criticizes mass production....The towering piece reflects the overpopulation of 'things,' and, thus, the people that own them."