I don't know about neighborhoods but I love history, among all the things pointed by @Bearofdistinction I would suggest:
Philadelphia water works, nearby museum, Rocky statue, park, etc.
Eastern State Penitentiary
http://www.visitphilly.com/resize/587x391/136/r/http/photos.visitphilly.com/eastern-state-penitentiary-int12-900vp.jpg
http://www.easternstate.org/sites/easternstate/files/2017-03/BT31-forweb_0.jpg