You need only one day to cover Philadelphia. But to do this, A better plan will be needed.
The Boathouse Row, Reading Terminal Market, Independence Hall, Benjamin Franklin Parkway, City Hall, Liberty Bell are the must watch. Do not forget to have cheesesteak. You will also find thousands of statues in this old city.
Start with the City Hall, arrive there very early in the morning. Do not forget to check my favorite statue “Government of the People” just beside of City hall.
Then start walking towards the Philadelphia Museum of Art. You will get Love Park, Logan Square. continue walking, you will get The Franklin Institute (science museum). Then Rodin Museum. And Finally the art museum. But this is not the end, behind the museum you will get the Boathouse. However, the boathouse Row looks better from other side of the river. Thats it from this side.
Now cross the city hall, go to Independence Hall, Liberty bell, Independence visitor Center, Benjamin Franklin Museum, National Museum of American Jewish History, Museum of American Revolution all are in same place. Then go to Penn’s landing, have a river cruise to watch the city skyline. Go to Independence Seaport Museum.
You can add the King of Prussia Mall in your list. Currently this mall is the largest Shopping mall in The US, which is around 20 miles north from the city. Good part is, you can cover Valley Forge with this mall