Where is the tallest building in the world?

Back in the 1800s, folks got excited about "skyscrapers" that were a whopping 10 stories high. Imagine telling your great-great-grandpa that his "skyscraper" apartment was basically a bungalow by today's standards.

But in 1889, Paris decided to show off, erecting the Eiffel Tower at a dizzying 984 feet. For years, it was the world's tallest structure, probably because everyone else was too busy trying not to get vertigo looking up at it.

As humans, we have an odd compulsion to build stuff that outlasts us. Our legacy? A global game of "My Tower's Bigger Than Yours." Since 1889, we've been in an architectural arms race, each city trying to outdo the last.

Today, buildings in some places are just needlessly tall, but it's still impressive. Where in the world is the tallest building ever constructed (so far)?