18. Burj Khalifa, Dubai, United Arab Emirates

Height: 828 meters
Cost to build: US$1.5 billion
Completion date: January 2009
Fast fact: Not only is this the world’s tallest building, it is also home of the world’s highest mosque, on the 158th floor. The tower is more than twice the height of the Empire State Building in New York.

 Size isn't everything -- that's what the little guys always say. Standing 828 meters high and weighing half a million tons, Burj Khalifa towers above its city like a giant redwood in a field of daisies. It has been been the world's tallest building since 2010. Gigantic doesn’t begin to describe it. This “desert flower” stands out comfortably among other skyscrapers and has become the symbol of Dubai’s bling, which often goes hand-in-hand with figures of per capita carbon footprints –- which Dubai also tops.