I recommend clicking on the image to expand it. One thing that I think is really interesting about this photo is that you can see a striking contrast between the old and new buildings. The old buildings are out in front (along Michigan Avenue) and have a brownish/yellow tint to them... the new buildings tower in the background and have a greyish/black tint. The older buildings almost look like they are fortress walls protecting the city behind it.
It's really interesting to look back at old photos of the Chicago skyline and see how much it has changed over the years.