I love love love Reading Terminal Market! It's located at 12th and Arch streets in Center City. If you like food, come here. If you like people watching, come here. If you like music, come here. There is always something going on and it's different everyday. I'd highly recommend coming if you're ever in the city.
There is every type of cuisine you could imagine - Thai, Chinese, Mediterranean, Middle Eastern, Italian, American and the list goes on. Oh and did I mention it's not all food? Yep they have little clothing and jewelry boutiques, cook books, crafts, flowers and more. The Pennsylvania Dutch also have a big presence at the Market. There are over 80 merchants here.
There's a piano player near one of the seating areas that I think adds a nice touch. Every Wednesday they also have a live local musical act to entertain you during lunch time.
J and I have been shopping here for all of our produce and seafood as we've compared prices and most things are less expensive than the grocery store that we go to for other items. The produce merchant we've been using even has a 10% discount for students that I will be taking advantage of as soon as I get my student ID!
Lastly, the Market offers tours and cooking classes. We haven't taken advantage of either of these things yet, but it's another thing that I'm adding to my Philly to do list!