You will find English courses all around the city. Even if you have a very good level of english I would recomend you to enrol on a course so it is a very good way to know people and to have other references of the city.
The courses I recomend you are:
- Women’s League MIT. http://web.mit.edu/womensleague/events/class.html .
Classes meet Tuesdays and Thursdays from 9:15 to 11 am during both the fall and spring terms. Beginning, intermediate, and advanced levels are offered. Cost is $80 per term with books provided. Child-care is available, on a first-come, first-served basis, for $150 per child per term. Registration is usually in September and February.
- Harvard Extension School. Link http://www.extension.harvard.edu/
- Kaplan. This school can help you to prepare exams to acces to the university or job, like : GMAT, TOEFL, GRE. Is located in Harvard Square. For more information visit the web. http://www.kaplaninternational.com/schools/usa/learn-english-boston-harvard.aspx
- Cambridge Center for adults education. (2 min walk from Harvard Square)
In this site http://www.ccae.org/ you will find all kind of courses: photography, painting, cooking, english, french, dancing…I am taking a course there and I am very happy with that.