Cira Green is a newer location for downtown since its only a few years old.  Located on the roof of a parking structure along the Schuylkill, surrounded by the Cira Center buildings, its one of my personal favorites just for relaxing on a nice day.  But for photos it works nicely as well.  The grounds are simple with a few areas to get cozy in the grass lawns that it has.  It has a couple spaces that work well to get the skyline involved and like I mentioned, you are in a valley between two skyscrapers so its always nice to work them into some shots as well.  

*As of now, there are no formal permits needed but this is subject to change.