there's an old "documentary" from the early 60's with Bacon talking about his big plans for Center City - part of it is him making fun of the then current plans for Independence Mall. Independence Mall and most of the "historic" bldgs. didn't exist at that point. He was arguing that buildings should frame the mall itself, not the streets around it, because he said "no one will use this mall if it's just an empty void" and he was right. He was right - no one did use it. It gets a lot more traffic now that they've moved the Liberty Bell and the Visitor's Center - part of his original suggestion.
I can understand his problem with the siting of the Constitution Center. Penn originally laid out 5 public squares. (center square is now covered by city hall)
Independence Mall covers all of the blocks between Washington Square and Franklin Square but one block to the east. The Constitution Center cuts Franklin Square out of the picture and Franklin Square already had enough problems.
The north, south and east sides are taken up by approaches to the Ben Franklin Bridge (676 East) and the west side is a main drag leading to 676 West and I-95.
(676 is the yellow line) Putting the Constitution Center at the top of the mall was more or less the final nail in the coffin.
He was also talking about his other plans in the documentary , ironically, building 676 as a CBD loop. Only the Vine St. portion got built. The other part was supposed to go down our beloved South St. Building 95 along the Delaware that destroyed the oldest bldgs. in the city. And to his credit - building a hotel on the waterfront (that was finished 2 years ago) and building the commuter rail tunnel and Market East station.
at the top of the picture you can see windows at street level with sunlight coming in. Just above the front of the train you can see the windows at concourse level where the subway connections are, and of course at the bottow are the platforms. 2 tracks eastbound and 2 tracks westbound.