In 1980, Shenzhen was established as China's first special economic zone. Since then the city has grown rapidly. Today the population is estimated at around 12 million. Shenzhen is part of the Pearl River Delta Metropolitan Region, one of the most densely urbanized regions in the world, which also includes Guangzhou, Huizhou, Dongguan and of course, Hong Kong. The Pearl River Delta is one of the most economically dynamic regions in China. This is where iPhones are made. In November 2006 I made a day trip from Hong Kong to Shenzhen. There's only so much you can see and do in a day, but I was struck by the fact that buildings that didn't look much older than 20 years were being demolished to make place for larger settlements.