Welcome to Shenzhen — China's youngest megacity. 40 years ago this was a fishing village of 30,000 people. Today it's home to 17 million, Tencent's headquarters, the world's largest electronics market (where you can prototype a phone in 12 hours), and a metro system younger than its average rider. Where Beijing has 3,000 years of history, Shenzhen invents the future every quarter.