Thanks for the list. It's been about 15 years since I visited Philly. Now that you mention it I remember the Mall there as well.
The AQ threat that the Liberty Bell will melt is even more ominous when you add all these incidents together.
The Federal Mint is near by .. if I recall back from 9/11 .. they thought that building was a possible target
Actually .. there are a number of targets in Philly they could hit if that's what they want