Tate Modern’s Switch House: art comes first

The Observer’s art critic takes a tour of the gallery’s new extension and finds a beautifully cogent chronicle of art movements from the past 60 years• Rowan Moore, the Observer’s architecture critic, appraises Switch House from the outsideWith the opening of the Switch House, Tate Modern has become the biggest museum of modern art on earth. But did it not exceed every rival already? The only achievement in doubling the size, Jeremiahs predicted, would be to increase the s