Sandwiched in between the Art Museum District and Center City is Logan Circle. Logan Circle is my top picnic recommendation with its well groomed grounds and the killer Swan Memorial Fountain. This park also has the fewest homeless as they prefer the more touristy LOVE Park or the trendy Rittenhouse Park (link). This is a perfect lunch spot if you are visting the Natual History Musuem, The Franklin Institute, Moore College of Art or the Philadelphia Free Library. There are a few carts in this area but over all I would suggest you grab something at WaWa around the corner, Honest Tom’s Tacos which is a food truck that is usually parked close by or DiBruno Brothers.
I am seeing a loto of reviews that say how dangerous it is to cross the street to get to the fountain and how only the brave attempt it. I am going to assume this was before all the light and cross walks because I just cruised across to the circle the other day with two kids under two and I never once feared for my life. Just wanted to call that out.