The probably apocryphal legend has it that Mrs. O'leary's cow kicked over the lantern that started the great Chicago Fire of 1871 which destroyed 2000 acres and 18000 buildings in the city of Chicago. It was, however, the aftermath of the fire that revolutionized the world. This was mostly due to one man, namely, Pittsburgh steel magnate Andrew Carnegie .
       Since the beginning of civilization buildings had been erected with stone foundations. This limited the practical size of structures to about 50 ft. ( The Pyramids are some 400 ft. high, but that was a massive and not cost effective undertaking ) Carnegie, looking for new markets for his steel, suggested Chicago be rebuilt using steel foundations. The incredible strength of steel and its almost unlimited availability due to Carnegie's streamlining of the Britisher Bessemer's revolutionary process for making it allowed buildings to be practically constructed to hundreds and eventually one thousand ft. high. Thus the modern skyscraper and twentieth century urban life was created. Not coincidentally, it also made Andrew Carnegie the richest man in the world.