Cincinnati girl here with some questions about Boston
I posted this on your local nest board as well...
My husband, son, and I are coming to Boston next week. We are actually staying at my uncle's summer home in Chappaquiddick and then spending a couple days in Boston.
Few questions....
We will be doing the long ferry ride/bus ride back to Boston on Sunday and then spending the rest of Sunday, all day Monday, and then a half day on Tuesday in Boston. I want to see as much of the city as possible. How much do you think we can do with an 18 month old in a stroller? I am a big history buff, so I want to do Freedom Trail. Any must-sees that a toddler would enjoy?
Also, my husband "needs" to see a game at Fenway. We haven't bought tickets yet. Any tips on how to get cheap tickets?
And finally, (and probably a stupid question), if we take cabs, do we need to install my son's carseat in every cab? Or is he fine sitting on our laps in the back of the taxi? (We don't do cabs very frequently in Cincinnati).
Thanks so much!! 
Re: Cincinnati girl here with some questions about Boston
You need a car seat for cabs.
Boston is one of the most walkable cities in the U.S.
The Freedom Trail will take you through the majority of the historical sites in Boston.
Eat in the North End (Italian) - you can't go wrong. For casual food atmosphere, but restaurant quality food go to il Panino Express on Hanover
Street. Then go to Mike's Pastery for desert and Cafe Victoria or Cafe Pompei for cappucinno.
Boston has a great Children's Museum and Aquirium if it rains.
Actually, you don't need a carseat for cabs. Obviously I would recommend one (cab drivers here....not good!), but legally you don't need one. I suggest an umbrella stroller and take the T most places.
Freedom Trail is great. If you DC gets tired skip the last mile and a half or so (out to Charlestown and the Constitution, etc). Bring a swimsuit for your DC and go to the Frog Pond on Boston Common and then to the public Gardens for thre Make Way for Ducklings statue and a ride on the swan boats.
You could also do a trolley tour - one of the hop on/hop off ones would be best with a toddler. Duck Tours are great, but not at that age.
For Fenway, if you don't have tickets yet you are out of luck unless you want to pay a scalper or know someone with season tix/company tix, etc. . sorry!
On the Red Sox game, you may potentially have some success with day of tickets for the Monday night game (https://boston.redsox.mlb.com/bos/ticketing/gameday.jsp). My husband and I have had success with purchasing day-of Grandstand tickets after work for weeknight games. Good Luck!
You can also try aceticket.com or stubhub.com for Red Sox tickets. I have purchased many through both sites.
My 1 1/2 year old nephew was just in town and LOVED the Children's Museum. It is perfect for toddler's, definitely check out their Playspace exhibit specifically designed for 0-3 year olds.
The aquarium was a hit too, except he couldn't see in the any of the tanks because they were too high off the ground so we had to keep lifting him up. His mom's back was sure sore after that!
Good luck and have a great visit!