The Great Chicago Fire of 1871 burned the heart of Chicago, starting on DeKoven Street on the Near West Side (558 West, 1100 South) and going north to Fullerton Avenue.
The Loop was destroyed, as can be seen in these maps.
City Hall, Palmer House, Field, Leiter & Co.—all gone. But, with the rubble still smoking, Chicago began rebuilding. Just two years later, it published Rebuilt Chicago, a "coffee table" book with beautiful illustrations showing the city's progress.
For photographs of the Loop, see the photograph collection in the reading room of Special Collections. Or browse these books with photographs and drawings from the fire: