This is a wonderful activity, whether you're a local or from out of town. You can get on without a ticket at any of the stops, and then pay for the ride later when the tour gets to the ticket booth at what is technically the first stop. When you get on without a ticket, the driver holds your credit card so that you don't essentially get a free tour by getting off before the stop where you buy the tickets. This is a great feature, because if you've driven your car to the USS Constitution and have parked there, you can see the ship and museum, and then board the trolley there, without a trolley ticket. If this feature of being able to board at any of the stops without a ticket, didn't exist, we'd never have been able to take the tour.
Our driver was very entertaining and engaging. I learned a lot, but I've got to say - for the absolute best informative tour EVER, take the Boston Harbor Cruise narrated live, by David Coffin - blew me away!!