Nicholas Serota: The great transformer

Which are the three most important museums of Modern and contemporary art in the world? The Pompidou in Paris, the city that defined art until the Second World War. MoMA in New York, the city of the post-war period. And Tate Modern in London, the city that may never have defined art, but is about to rip up the classic two-city narrative of the Modernist canon for good.The seeds were sown a long time ago. The much-maligned 2001 Century City showart from Paris, Vienna, Moscow, Rio, New York, Lago