In 1992, construction crews working near the Kinzie Street Bridge punctured the ceiling on one of the abandoned tunnels under the Chicago River. It started leaking, but, in true Chicago fashion, nobody did anything about it.
After several weeks the leaking got worse and completely flooded the tunnels. The water rose so high that it flooded the basements of many downtown buildings. Electricity and natural gas was knocked out, and the entire Loop, Financial District, City Hall and even the subways, Board of Trade and Chicago Mercanitle Exchange were closed and evacuated.
The damage was estimated to cost about $1 billion. Some people didn't return to work for a month, and the subways were rerouted for weeks while water was pumped out of the tunnels. The flood cost the city even more money when the buildings and insurance companies sued.
What was really strange about the flood is that nobody was injured, and if you were standing on the street you would never know anything was wrong.
Even funnier: the city had absolutely no idea where the water was coming from until they started finding fish everywhere.
Dehumidifiers snake out of DePaul University's Loop building at Jackson Boulevard and Wabash Avenue. The dehumidifiers were deployed to remove moisture from the air in the building's flooded basements. (Image and caption via the Chicago Tribune.)
The Great Chicago Flood of 1992 was an odd calamity that turned the Loop into a "soggy ghost town." It became an international news phenomenon, a joke for weeks on late-night talk shows and an item satirized by political cartoonists like the Chicago Tribune's Jeff MacNelly. (Image and caption via the Chicago Tribune.)
A passerby looks at a flood sale sign in a hand bag store at Wabash and Randolph Streets. Items in numerous downtown Chicago basements and sub-basements were damaged or destroyed due to the Great Chicago Flood. (Image and caption via the Chicago Tribune.)