Louis Sauer's Penn's Landing Square just to the south also great (Sauer seems to receive far too little credit ever for a febrile career)
plenty of other interesting modern infill.. not all of it great, some drab and I missed some I had seen previously, but often intriguing
I wrote about all of this a few years back https://www.bloomberg.com/news/articles/2017-07-08/the-pleasantly-modern-architecture-of-philadelphia-s-society-hill