*free on wednesdays from 4 to 9.45 p.m
*free for Harvard students and for Massachusetts residents every Sunday morning from 9am-noon, and on Wednesdays (September through May only) from 3-5pm. Proof of residency is required.
*always free
*always free
*always free
*always free
*always free
*free on every thursday from 5 to 9 p.m
*free on every saturday from 10 a.m to noon for cambridge & massachusetts residents
*always free