Herzog and bird nestWe've been waiting for master Swiss architects Herzog & de Meuron to leave their mark on an American city. The place: Minneapolis. The time: very definitely nowMarch 21 issue - As everyone knows, winter is still blasting the Midwest, and besides the blustery snow, a giant ice cube has landed in Minneapolis─and it's not going to melt by spring. "A big ice cube for Ice City," jokes the avant-garde European architect Jacques Herzog, one half of the Basel-based team of Herzog & de Meuron, who've designed the expansion of the city's Walker Art Center, opening next month. The tour de force of their building is the silvery five-story cube, with its daredevil cantilevered corner hovering over the entrance─anchored by hidden tons of steel and concrete─and the whole shebang wrapped in shimmering aluminum-mesh panels that look as light and luscious as crumpled silk.What makes this a very big deal is not just that the building is so cool but that we've been waiting so long for these Swiss masters to build something major in the United States. When they came to America in 2001 to collect architecture's biggest honor, the Pritzker Prize, they were barely known here. Their award was presented at Thomas Jefferson's Monticello─an incongruous setting given what their architecture looks like─and on the day of the ceremony you could spot the pair a mile away on the quaint streets of historic Charlottesville: they were the uber-hip Euro-guys dressed in black. Their breakthrough project, the Tate Modern in London, had just opened the year before, and Herzog and Pierre de Meuron were young for Pritzker laureates (they were each 50─kids in a profession of late bloomers). Since then, th...