Boston Hop-On Hop-Off Trolley Tour (Trolley) - Boston Tours
Same principle as the Duck tours but you can get on or off at any of the stops, do a museum/historical site/snack and then get back on the next trolley.
Catch a Red Sox game if you can. If they don’t let you catch, just get seats in the stands.
Fenway Park is Boston.
I’ve heard that with the Sox fantastic start this season, you can buy tickets from scalpers for well below face value if you’re willing to wait until the 2nd inning or so. Those guys are getting reamed this year (deservedly so).
If you’re willing to brave the Red Line ($1.70 fare each way, last I checked), you can also cross the river and eyeball some of the old things in Cambridge. MIT and Harvard have their own campus tours on top of everything else, and there are various historical things to boggle at. Not terribly crowded going out to Alewife during the afternoon, nor going inbound to Park Street during rush hour – everyone else will be going the other way, trust me. 
(I just moved here a year ago, but I was unemployed for the first month or so. I did a LOT of random wandering. Boston is a very walkable city, which you may appreciate after being stuck in an airplane for a while.)
No one has bothered to mention Faneuil Hall?
go to Faneuil Hall.
I mentioned Quincy Market. Same thing.
$2.00 if you don’t have a Charlie Card.
I thought they were the same. 
(which is why I didn’t mention it)
Faneuil Hall is the small building on the Government Center side. The three parallel buildings are Quincy Market (plus North and South Market).
True enough.:smack:
Sorry.
It was mentioned in the first reply.
Rio! The song is Rio!?
Technically they are different, but they are so close together that it’s hard to visit one without visiting the other.