Dubai is one of the world leaders in over the top architecture. But this might take the cake. They are planning to build an underwater tennis court that would cost an esitmated 2.5 Billion dollars. This is what an artists rendering of the court looks like and check out http://www.forbes.com/sites/eustaciahuen/2015/11/30/latest-look-at-the-worlds-first-underwater-tennis-court/ for more information on the unbelievable court.