As of 2011, the Burj Khalifa, a skyscraper built from 2004 to 2009 in Dubai, is the tallest structure in the world. It stands 828 meters (2,717 feet) tall -- more than half a mile -- and consists of more than 163 inhabitable floors below its spire. All told, the massive building contains 206 stories and dominates the Dubai skyline [source: Glass Steel and Stone]. The Burj Khalifa is the latest in a long line of skyscrapers that push architectural design to its limits.
Though we've been building homes and offices and businesses for hundreds of years, it wasn't until the year 1884 that the word "skyscraper" became part of the architectural lexicon. Skyscrapers are usually tall, of course, but there's no hard-and-fast rule declaring that skyscrapers have to reach a certain height. So what makes a skyscraper a skyscraper? It all started with the Home Insurance Building in Chicago. The 10-story structure is widely recognized as the first in the world to use a steel skeleton to support its weight. That innovation went on to become the primary qualifier for buildings to be classified as skyscrapers in modern architecture [source: Chicago Architecture Info].
Once architects began using iron and steel in construction, they were able to build taller, stronger structures without relying on thick, heavy stone walls for support. Those incredibly strong metals paved the way for buildings 10, 20 and eventually over 100 stories tall. But strength only goes so far -- the taller buildings get, the more complicated construction becomes. Architects have to deal with issues like wind resistance to ensure heavy winds at high altitudes don't twist and destroy their buildings. Today's architects wouldn't even have such lofty concerns were it not for the Home Insurance Building and its designer, a man named William Le Baron Jenney.