First and foremost, I want to warn all of my readers that I’m going off the radar for a week starting on Sunday, so this is likely to be my last post until I return.
Second, regarding the concourse map which was featured in my last post, I have since found that there is at least one copy of this map remaining in a public space. The map I know of can be found near the northern stairs in the concourse by the 15th Street platforms for the Market Frankford El and the eastbound Green Line platform. For reference, if you were to get off of the El at 15th street, you would want to walk away from the sculpture of the giant clothes pin after exiting though the turnstiles.
The Map is about three feet on a side, quite a bit bigger than I had remembered it being, and no longer accurately reflects some of the Suburban Station area of the concourse.
Finally, I was tipped off that the program which I posted a video clip from last time is called Secrets Beneath the Streets, and was produced by WHYY TV-12. In addition to City Hall, the program looks at locations such as the abandoned subway platform in the base of one of the columns of the Ben Franklin Bridge and the Philadelphia Water Works.