Only in a big city are rooftops used considered additional square footage. When I was single living in Manhattan my girlfriends and I would often sneak up onto the roof (technically we weren’t allowed up there) to watch the sunset, eat thai take out and attempt to analyze certain boys that were causing us unnecessary grief. Anyway, the coolest thing to do with a Manhattan rooftop is make a beautiful garden out of it. Found a flickr stream on stumbleupon called Rich People’s Rooftops with gorgeous photos of rooftop gardens in Manhattan.