Londons Heathrow Airport is one of the worlds busiest airports, serving 72.3 million travelers in 2013 alone, and demand for more flights is only growing. At least if London Mayor Boris Johnson gets his way. In order to keep up with skyrocketing demand projected for Heathrow into 2050s, Johnson years ago began advocating that Heathrow be closed and a new airport be built 40 miles east on a rural island in the Thames Estuary. Still, the London Mayors Office has gone ahead and commissioned three outlandishly ambitious proposals from leading architectural firms for what to do with the area now occupied by Heathrow if it does end up moving.