Will be going to Philadelphia for 4 1/2 days with 13 year old grandson. What shouldn't we miss???

It would cetainly help to know your interestes and those of your grandson. Phila. Historical district is wonderful. You can get tickets for Independence Hall at the Visitors Center. They are free, but give you a specific time to go. I would pick them up first. The Constiturion Center is also great. The Liberty Bell is right in the same area. There are some great walking tours of the ares.
I think your grandson would like The Franklin Institure Museum. There is a lot to see and do in Phila.
You can go to www.gophila.com for loads of info.
Tell us some of your interests so we can be of more help.

That was supposed to say Franklin Institute Museum.

One of my friends from work (I work for a marketing company in DC) just reminded me that you can't go to philly without visiting the famous cheesesteak stands. Pat's and Genos are in the middle of the city and you have to visit...it's definitely part of the philly experience. Also, the liberty bell is a must-see.

Grandson is a History buff - took him to Washington DC two years ago - his choice this year was Philly.

If he is a history buff, you cannot miss the National Constitution Center. It is a great museum. Do not miss the live show; it is very powerful!
Obviously, there is Independence HAll, the Liberty Bell, Betsy Ross house... You are coming to the right place. I have also heard that the Lights of Liberty Tour is quite interesting; I have seen BOGO coupons around so keep your eyes open!
Valley Forge Park is about 30 minutes away; it would be perfect for a history buff!
For lunch, make sure you get to Reading Terminal Market (they are closed on Sundays). Also, Chinatown is always fun!

There's so much to do--it's a great choice by your grandson! If you haven't seen this, here's a Franklin-themed walk; it's his 300th birthday, and it's being celebrated all over Philadelphia! (So he was from Boston and lived in London and Paris for a good part of his life...we still claim and honor him for his wonderful involvement with the city's development.) See the walk here: http://www.fodors.com/forums/threads...1&tid=34808371 along with a website for some others.

In a totally different history area, the University of Pennsylvania Museum of Archaeology and Anthropology is very interesting as well.

And don't miss going to Capogiro at 13th and Sansom for some of the nation's best gelato.

Happy trails!

Maybe you both would enjoy a tour of the Battleship New Jersey. It's just right across the Walt Whitman Bridge into New Jersey.
http://www.battleshipnewjersey.org/visit/