Excellent guided tours
The most famous part of Philadelphia is the Mile, so called because it has historically been the richest square mile in America. It occupies 4 blocks and is bordered by the Delaware River to the west. Every day there are excellent guided tours organized either on foot or by minibus companies like Plash. At certain points actors in period costume will delight you with songs and stories about life in historical Philadelphia. Look out for the "gazette", that you will find at your hotel or the visitor center, which lists the times of all the events.