Looking for RV parks near Boston MA

Wow, lot's of great advice here. I now have a pretty good idea how we're going to do this. While I have taken my truck into some pretty tight places I absolutely hate, hate, hate most urban parking garages. They are not designed for pickup trucks. I think it will make most sense to leave the truck at the train station parking lot and take the train.
I understand there is some kind of walking trail that takes in the major historic sites. I can't remember the name of the trail though. We will want to take that.

edit*** Never mind, it's the Freedom Trail, I remember now.