Next to the Federal Reserve, China holds most of America's debt. A recent National Public Radio broadcast said that China was acting like "the big man on campus" (a more polite radio-friendly term than I imagine the correspondent would use in person!). China manufactures an enormous number of products for American companies – all that is well known. Somewhat less well known, but not entirely unfamiliar is the risk of a real estate bubble in China as apartments in places like Shanghai are going for New York City style prices.
What I didn't know and what blew me away is that there are purportedly dozens of ghost cities that have been built by the government, but in which nobody actually lives. If you click on the link, it will take you to actual photographs of these places – the scale of it is quite amazing and alarming!