Tuesday–Sunday, 10am–5pm (closed Mondays and major holidays)
Harvard Art Museums · Cambridge
The Harvard Art Museums are free for everyone, every day they're open: Tuesday to Sunday, 10am to 5pm, just outside Harvard Square. Check in at the Visitor Services desk when you arrive.
The state's Commonwealth Museum at Columbia Point in Dorchester is free to visit with free parking. Open weekdays 9am to 5pm; closed weekends and legal holidays.
Most Wednesdays at 7:30pm (Oct–Mar; 8:30pm Apr–Sep), weather permitting
Judson B. Coit Observatory, Boston University
Boston University opens its rooftop Coit Observatory to the public most Wednesday evenings, weather permitting, to look through telescopes and learn some astronomy. From October to March the program starts promptly at 7:30pm, with no entry once it begins. Tickets are free (up to 5 per person) and released on Eventbrite around 11am on Thursdays; walk-ins get in if there's room. It's cancelled for clouds, haze or rain: call 617-353-2630 (no earlier than two hours before) to check. Stairs only, dress warmly.
Verified Oct 27 · bu.edu
Catch: Free ticket required (released Thursdays on Eventbrite, up to 5 per person) · No unaccompanied minors
Boston College's McMullen Museum charges no admission and has free parking. Open weekdays 10am to 5pm and weekends noon to 5pm (no museum parking on BC home football days).
MIT's List Visual Arts Center is free and open to all, Tuesday to Sunday from noon (to 7pm Wednesday and Thursday, 6pm other days), in the Wiesner Building near Kendall Square. Closed Thanksgiving week's Wednesday–Thursday and over Christmas and New Year's.
Mon, Wed–Fri 9:30am–4:45pm; Tue 9:30am–7:45pm; Sat 10am–3pm
Massachusetts Historical Society · Boston
The Massachusetts Historical Society's galleries and research library on Boylston Street are free and open to the public: Monday and Wednesday–Friday 9:30am–4:45pm, Tuesday 9:30am–7:45pm, Saturday 10am–3pm. Last entry is 45 minutes before closing. Building tours are listed on its calendar.