Biggest show by Ai Weiwei to open in Berlin without him The biggest-ever exhibition by China's best known and boldest contemporary artist, Ai Weiwei, opens in Berlin Thursday with his signature brand of politically explosive works given pride of place. The show at Berlin's Martin Gropius Bau museum comes one week after a landmark state visit to Germany by Chinese President Xi Jinping. Its 18 rooms of mainly new installations pack a stinging critique of official corruption, political repression and capitalist excess in the world's most populous country. Images and soundbites.