The top two breweries to visit in Boston are Harpoon and Samuel Adams.
1) Harpoon Brewery is located in the Seaport District of Boston (about 10 minute cab from Back Bay). They do offer tours but they also have a large brew hall. I recommend skipping the tour and going to the brew hall and getting a flight of beer and a few orders of their doughy pretzels. The pretzels come in three flavors: salted, cinnamon sugar, and garlic. They are amazing!
Tour Schedule: Cost is $5, includes beer tasting
Mon – Thu from 12:00 PM to 5:00 PM (starting on the hour, last tour at 5p)
Fri from 12:00 PM to 6:00 PM (starting on the hour, last tour at 6p)
Saturday from 11:20 AM to 6:00 PM (starting every 20 min, last tour at 6p)
Sunday from 11:30 AM to 5:30 PM (starting every 30 min, last tour at 530p)
For more information or directions to the brewery visit:
2) Samuel Adams Brewery is located just outside of the city in an area called Jamaica Plain (about a 10 minute cab ride from Back Bay) If you are looking to go on a tour I recommend the Sam Adams Brewery over Harpoon. Tours leave every 45 minutes and last about 1 hour. Tours are first come first serve and do not take reservations. The tour is free but they do ask for donations (usually people give 2-5 dollars). After the tour you sit down at the bar and they let you try multiple beers for free! Since you will be in the Jamaica Plain area I recommend stopping at a restaurant called The Haven. It is one of my favorite restaurants in Boston and it is different from anything else you will find. I recommend trying the Scottish Egg, the burger (best in Boston), and the fried mars bar for dessert. It is definitely not healthy but so good! To make a reservations visit http://thehavenjp.com/
Monday – Thursday: 10:00am – 3:00pm
Last tour starts at 3:00pm (gift shop closes at 6:00pm)
Fridays: 10:00am – 5:30pm
Last tour starts at 5:30pm (gift shop closes at 6:00pm)
Saturdays: 10:00am – 3:00pm
Last tour starts at 3:00pm (gift shop closes at 4:00)
For more information or dirrections to the brewery visit: http://www.samueladams.com/boston-brewery/brewery-faqs