I don't know anything about the area, but that looks like a great park - I like it when things from the past are repurposed for the future
last time I was in Chicago, I spent some time up on the Bloomingdale Rail "trail"
http://en.wikipedia.org/wiki/Bloomingdale_Line
http://www.bloomingdaletrail.org/
it would be cool to see a proper park made of that
