text:  <unk> 's wife died in 1834 ; the couple had no children . The major <unk> of the <unk> estate was Harvard ( which received an estimated $ 100 @,@ 000 ) , although <unk> were also made to the American Academy of Arts and Sciences and the Massachusetts Historical Society . The <unk> estate passed through several hands and was subdivided over time . The mansion was saved from demolition by the <unk> Place Society ( established for the purpose of preserving it ) , which now operates it as a museum . It was declared a National Historic Landmark in 1970 . 
  