I just took a look through it, and the current symbol sets for modern city maps are a little lean. Keep in mind, everything is VERY top-down. But here's a sample. I just tossed things out onto a background, so it's in no way the full potential of the program, but it'll give you an idea of what you're looking at. This contains only a few things as well. The skyscraper (the huge thing in the upper left) contains some add-ons, and you can expand it to your heart's content. There are some symbols for smoke or smog coming out of a rooftop too, which may work for your factories. Anyway... Hope this is at least a little better of an idea.

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