Lessons from the world's most thriving megacity

Forty years ago, Shenzhen, China, was little more than a cluster of villages, home to a few hundred thousand people. Today, it holds roughly 20 million residents and ranks among the world's fastest-growing megacities. Yet, unlike other urban centers that have ballooned at similar speeds - Mumbai or Lagos, for example - Shenzhen has largely sidestepped the air pollution, overcrowding and failing infrastructure that often accompany rapid expansion. The World's Jeremy Siegel visited Shenzhen and breaks down how that was accomplished.