The Grand Lodge of Massachusetts is the administrative headquarters of Massachusetts Freemasonry, as well as the home for more than 20 Masonic organizations meeting in Boston. It houses the Samuel Crocker Lawrence Library, one of the largest and most important Masonic collections in the world. The beautiful, historic building is open to the public for free tours on Monday, Wednesday, Friday, and Saturday between 10:30 and 2:00 (call to confirm on holidays).