For centuries, Beijing was closed off to the world, turned inward and literally built around the imperial Forbidden City, the emblem of all that was unknowable about China. But now the capital is reinventing itself to reflect China s global influence, progress, and prosperity. When Tom Scocca arrived an American eager to see another culture Beijing was looking toward welcoming the world to its Olympics, and preparations were in full swing to renew itself.

Scocca discovered a city of contradictions modern and ancient, friendly yet wary, bold and insecure. He talked to scientists tasked with...