We will be visiting PA in April and only have 4 days to try to take in a few historical sites. We want to go to Valley Forge National Park for sure. We are hesitant about driving from the King of Prussia Area into Philadelphia just because I read on a couple of posts that driving in downtown Philly is really bad. I learned my lesson a few years back when we drove to NYC from Washington, DC. Is there a rail system that we could park our car and ride into Philly from the King of Prussia Area? Or for that matter, any area that is pretty close to Valley Forge.