• Arnold Arboretum of Harvard University
Technically this isn't in Boston as Cambridge is it's own distinct city, but we still think it's worth heading over there to see the sprawling 265 acre arboretum. What you'll see will differ depending on the time of year, and be sure to stop by in the fall for a free guided tour of the foliage.
• Boston Common
Famous for being the oldest public park in the United States, Boston Common is a beautiful green space near downtown. It's not a place to spend an entire day, but if you've got an hour to kill it's a great place for a stroll or a picnic. Feel free to bring the kids as the park boasts two seperate playgrounds.
• SoWa Open Market
Open seasonally (4/29 - 10/29) from 10AM to 4PM on Saturday and Sunday, the SoWa Open Market takes places in the SoWa arts and culture district of the South End. You can find local artisans, brewers, farmers, and chefs selling their wares from booths, card tables and trucks at SoWa and the people watching can't be beat. Just don't get there too late in the day, most of the good stuff will be gone.
• Fenway Park
Maybe you don't want to pay to go to a Red Sox game, or you don't have time, that's OK! Hour long ballpark tours are offered year round because everyone should see Fenway Park, it's an American institution. If you do want to see a game in this unique stadium, be sure to buy your tickets at least a few weeks in advance, games sell out early in this baseball obsessed city. Don't forget to have a Fenway Frank!
• The Freedom Trail
It's hard to escape the history of Boston, and no better way to see it than to follow the aptly named Freedom Trail. Stretching 2.5 miles around the city, The Freedom Trail consists of 16 historically significant buildings and is marked by a brick path running between them. Remember Paul Revere? His house is on the Freedom Trail, as is the Old North Church where local patriots used lanterns to warn of the attacking British before the battle of Lexington and Concort. It's worth the journey.
• Museum of Fine Arts
If you're not into museums you can go ahead and skip this one, otherwise you're going to need at least half a day to devote to this expansive museum. The original Museum of Fine Art opened on July 4, 1876, but the museum was moved in 1909 and has been in it's current location ever since. One of the unique things about this museum is it's collection of over 1,100 instruments spanning the years and the globe.
• New England Aquarium
Rainy day? While it's not the largest aquarium out there, there is still plenty to see at the New England Aquarium. The aquarium's Giant Ocean Tank is 4 stories tall and mimics life on a Caribbean reef. This tank really lives up to it's name, it holds 200,000 gallons of water and over 1000 animals of all shapes and sizes. If you get bored of that be sure to get up close and personal with a Harbour Seal and watch Great White Sharks in the aquarium's IMAX theater.
• Do a Bike Tour
Boston is a small city, but it's not that small. There is so much to see and only so much time, so you might want to consider a bike tour. The freedom trail takes a full day by foot, but it takes about half as long by bike. There are a whole host of great bike tours in Boston so why not see how the city looks on two wheels? In case you need a bit more motivation, it's like going to the gym without actually having to go to the gym. 2 birds, one stone.