This Day in History: <br />The Great Chicago Fire Begins .<br />October 8, 1871.<br />According to legend, the fire was sparked when a cow tipped over a lantern in the barn of Catherine and Patrick O'Leary.<br />The fire burned for almost three days.<br />The actual cause of the fire is unknown. .<br />Due to numerous wooden buildings, <br />sidewalks and streets, four-square miles <br />of Chicago was devastated by the blaze.<br />As many as 300 people were killed. <br />More than 17,000 buildings were destroyed. <br />100,000 people were made homeless.<br />But reconstruction of the city allowed for modern planning, including the world's first skyscraper buildings.<br />Less than 10 years after the fire, Chicago boasted a population of 1.5 million. The city had become a major transportation and economic hub
