The Burj Dubai (which was built without a purpose) cost $1.5 billion to build. A plate of rice costs an average of, lets say $1.00. So you could've used that money to feed around 1.5 billion people, give or take a few 100 million. That's around a bit less than 1 fifth the world population. I love the Burj Dubai and think it's an amazing feat of engineering, but
Humanity First. I think that's why what's needed is being built in the U.S, because of the economy most people can't put food in their stomach or bread on their table. The idea of the world's tallest is out of the question, in any city in the U.S, because it's not feasable (FAA etc.), and it just wouldn't look good, unless they're meaning to build some half a mile tall building in the middle of Nevada, or Nebraska.