I've read a lot of great articles in the last few months about friendships between women, but this one is extra great because it's all about Girls (as well as the recent novel How Should a Person Be? by Sheila Heti, which I really want to read now):
New York Times article about the show's filming locations in Brooklyn and about how someday, there might be a Girls-themed tour of the city: Girls Fans Interact with the Show's Setting \o/ (This article also has a link to a fun little Girls map of NYC.)