The Great Fire of 1871 in Chicago was the most devastating catastrophe to ever hit the city. For decades the city was affected by the fire which spread quickly throughout the metropolis. While it has been well established that the fire was not actually started by a cow, the fire is certainly an important part of American history.
Map from 1871 showing the areas of Chicago affected by the fire. Via/ NYPL
Birdseye view from top of waterworks, North side. Via/ NYPL
Tribune building and Custom House from interior Second Presbyterian Church. Via/ NYPL