Re: what a difference 250 years make
You're kind of exactly right when you suggest that maybe there are too many places of "historic" significance in Philadelphia, and it is interesting that you bring to mind Piranesi and his map of the Campo Marzio because that map/plan indeed records so many of ancient Rome's historic sites even though almost none of them still existed in Piranesi's time. Moreover, it is worth also keeping in mind that Piranesi was delineating a place/city more than 1400 years after the fact. It seems almost impossible to even speculate whether, for example, the old "Indian" trail of Ridge Avenue will even still exist in 3402. Then again, it would be fun to imagine what some future Philadelphia Renaissance or Baroque period might be like. Note Franklin and Piranesi are near contemporaries; Piranesi died 1778 while Franklin was in France.