It had taken about 40 years for Chicago to grow from a small settlement of about 300 people into a thriving metropolis with a population of 300,000, but in just two days in 1871, much of that progress was burned to the ground. In arguably the most famous fire in American history, a blaze in the southwestern section of Chicago began to burn out of control on the night of October 8, 1871. Thanks to The Chicago Tribune, the fire has been apocryphally credited to a cow kicking over a lantern in Mrs. Catherine O’Leary’s barn, and though that was not true, the rumor dogged Mrs. O’Leary to the grave.

Of course, the cause of the fire didn’t matter terribly much to the people who lost their lives or their property in the blaze. Thanks to dry conditions, wind, and wooden buildings, firefighters were never actually able to stop the fire, which burned itself out only after it spent nearly two whole days incinerating several square miles of Chicago. By the time rain mercifully helped to put the fire out, the Great Chicago Fire had already killed an estimated 300 people, destroyed an estimated 17,500 buildings, and left nearly 100,000 people (1/3 of the population) homeless.

Mrs. O’Leary and her barn remain a part of lore, but it also speaks to Chicago’s ability to rebuild that it’s almost impossible to envision a farm in downtown Chicago today. Chicago suffered a wide swath of destruction, but it had rebuilt itself within 20 years in order to host the World’s Fair, evidence that it was back and bigger and better than ever. Along with that, Chicago has maintained its status as the region’s biggest city and one of the most important in America.