NBN has collected some of the most important points you can make in your letter:

It was built in 1938 as a Public Works Administration (PWA) project. The PWA was established during the Great Depression as a large-scale public works construction agency to help revive the economy. It provided almost half the funding for the Library, pursuing its frequent mission of keeping private businesses afloat through public-private partnerships.

It was designed by the noted architect (and Newtonville resident) E. Donald Robb of the Boston architecture firm Robb & Little (his amusing obituary is here).

The stained glass windows were designed by Charles Jay Connick, a nationally known artist and also a Newton resident.

At the building’s dedication in 1939, Robert Frost read his poem “Mending Wall” whose opening line Connick engraved in one of the stained-glass windows. See here for pictures of Frost and one of the windows. 

The “Newton Public Buildings Survey", conducted in 2012, recommended the preservation and rehabilitation of the building.

The Historic Commission has already designated it as “preferably preserved”.