How about retracing the route of the former Milwaukee Road Chicago & Evanston Line?
You could start at the former Buena Yard, just north of Irving Park Road where it interchanged with the CTA via a ramp. Then follow it south all the way to where it at one time crossed the North Branch of the Chicago River at Kinzie and Kingsbury and joined the main MILW tracks along Canal Street where they Metra/Amtrak tracks now cross Canal. It ran on the east side of Canal Street after crossing by where the East Bank Club now sits.
Your route would be primarily on city streets like Lakewood and Kingsbury. You could take a side trip onto Goose Island.
Show what artifacts like embedded tracks in the pavement are still left.
These maps should help.
https://www.flickr.com/photos/39092860@N06/albums/72157715114878692Put your photos on Flickr also.
Tom