A walk along South Street is worth doing (tattoo parlours, trendy shops and some hip restaurant & bars). A look around the historic dwellings of the Society Hill area is nice too, the same with Penn’s Landing (by the river). I thought Philadelphia was a great place for walking around (it’s not that big) and taking in the sights (I’d recommend taking the red open-top bus to get your bearings and you’ll hear some very interesting pieces of historical trivia). There aren’t a whole lot of activities that you can do but I really enjoyed soaking up the atmosphere and found that there were plenty of bars and restaurants full of life even mid-week.