Skyscrapers were originally invented to facilitate a predicted boom in the popularity of transit by way of vine-swinging. The idea was that the top of each building would be outfitted with an arrangement of twisted metal "vine cables". A person would leap from their apartment window and swing from one vine to another until reaching his or her destination window. This is the exact reason why so many modern skyscrapers have such large windows. There was never supposed to be glass there, just an opening that people could leap in and out of.