The main tourism areas of downtown and "waterfront" are very walkable. Pick up the pamphlet, Pilgrim Path, A Walk Through History at the Visitor Center on Water St. near Al's Restaurant.
The GATRA Busses Phone:+1 508-801-2300, (http://www.gatra.org/pal.html). M-F 6:20AM-6:10PM, Sa,Su 8:20AM-6:10PM. Runs several routes from downtown. Wheelchair accessible.