Around 9 p.m. on Sunday, October 8, 1871, a fire broke out in or near Patrick and Catherine O’Leary’s barn in the crowded southwestern section of Chicago. The fire may or may not have been started by the O’Learys’ cow kicking over a lantern. Fanned by high winds, the fire burned out of control in the tinder-dry city for more than 24 hours, until rain on Tuesday morning finally extinguished the flames. Four square miles of the city, including the business district, the courthouse and the central water pumping station, burned to the ground. This illustration, published in Harper’s Weekly, shows the terrifying scene as thousands of Chicagoans flee the flames over the Randolph Street Bridge. More than 300 people were killed and an estimated 100,000 were left homeless. Yet in spite of the devastation, the city was so quickly rebuilt that by 1875, few traces of the fire remained.