Note the building behind with the slanted, square shaped roof. After building that they noted a problem - in the winter snow and ice would build up on it and occasionally slide down onto the people in the street below. To counter this unfortunate effect they installed heaters on the roof. Sadly, they did this without considering just how cold Chicago winters get. The water that ran off the warmed roof froze on the way down, and the people below got rained on my frozen skewers of ice. Then, and only then, did it occur to someone to install guttering...