Al Burj. Silly Big.

Nobody knows how big the Al Burj (not to be confused with the Burj Dubai) will be when completed, except that it will be bigger than the Burj Dubai which is bigger than anything else in the world.

It probably wont get built at the original height of three quarters of a mile, however this architectural monstrosity would have made almost every other skyscraper in the world look tiddly.