What else is there to do for a family visiting Boston, other then the Aquarium?

My family is thinking about visiting the New England Aquarium in Boston, MA...but what else is good for a family to do together that isn't very expensive?What else is there to do for a family visiting Boston, other then the Aquarium?
Unfortunately Boston is very expensive. however, the freedom trail is a historical path that winds through the streets of Boston. along the way you can visit historical areas like the meeting houses, churches, Paul Reveres house, the neighborhoods, and bakeries and restaurants. There are a lot of other museums like the museum of fine arts and the Isabella Stewart Gardner museum which are free on certain days. Boston also has a lot of parks in the downtown area like the common and the public garden and usually there are events going on there. you can also do the swan boat ride in the public garden (i dont know how much it costs though). also theres Harvard square and faneuil hall market place where there are usually art galleries and street performers.
boston childrens museum (dont know your kids age but if they are 12 or younger its good)

boston science museum

prudential center tour

if you have the time and have a rental car, go to the beach



http://answers.yahoo.com/question/index;鈥?/a>What else is there to do for a family visiting Boston, other then the Aquarium?
The most popular attraction for families is the Duck Boat tour. it tours the city and even goes for a spin in the Charles River. Everybody loves it but it is a bit pricey, around $30. Otherwise, go to the Children's museum, fanueil hall, walk the freedom trail. If it's a nice day, just walking around is fun, cheap and quite safe.