After almost 200 years at an Eero Saarinen-designed location in the posh Mayfair neighborhood of London, American diplomats will be moving across the Thames to a new headquarters in 2017. And today, Philadelphia-based firm KieranTimberlake took home a hefty commission as its design was selected for the new U.S. Embassy. If you think it looks like a castle, you're right: The $1 billion EFTE-covered cube even has a moat, which the architects hope will deter any unexpected guests. But the airy fin-like skin and a footprint that appears to almost hover--not to mention the garden notched out of an upper corner--make it feel friendly, transparent and green.

The Los Angeles Times' Christopher Hawthorne approves, noting that it "aspires to a different and broader set of values, primarily having to do with ecological responsibility and neighborliness within a tight urban fabric." KieranTimberlake's win is even more amazing when you see the short-list: They were up against Thom Mayne's Morphosis, Richard Meier & Partners Architects and Pei Cobb Freed & Partners--all of them Pritzker Prize-winning architects. Here are the renderings from the runners-up.

Morphosis

Richard Meier & Partners Architects

Pei Cobb Freed & Partners

[Los Angeles Times]