fun things to do in boston?

im going to boston with my little brothers tomorow (11 and 13) i was wondering what some fun things we could do? preferably cheap. we'd like to be outside walking around and stuff too.

freedom trail is interesting and FREE lol. the museums are not that expensive to get into they might enjoy the science or childrens museum. boston.com should have a link for stuff to do around town.

You can see a lot of Boston by just walking around. The Freedom Trail is one option. You can also walk from Boston to Cambridge along Massachusetts Avenue. When you get in Harvard Square there are lots of entertaining (and not so entertaining) street performers. There are some interesting stores there too and a delicious chocolate shop called L.A. Burdick.