The library also was designed by the noted Boston firm of Shaw (George Russell Shaw was related to Quincy Adams Shaw) and Hunnewell. Like the office (
HO17.1), the library was conceived in broad Italianate terms, but with traces of Queen Anne and Richardsonian Romanesque. Both are built of carefully selected dark- and light-colored mine waste (basalt) rock with red brick and red sandstone trim laid by Italian stonemasons. Queen Anne features are especially notable in the library's patterned chimney stack and end gable. The basement contained twenty-one bathrooms for miners and their families; the first floor held a vestibule, book delivery room, catalog room, librarian's room, and stacks; the second floor contained children's and adult's reading rooms and a hall or smoking room; and the attic held a meeting gallery. Erected, furnished, and equipped with thousands of books shipped from Boston by the C&H company, the library served the company's employees and residents of the Calumet Township school district. Thus, with the reading rooms upstairs and baths downstairs, Alexander Agassiz took care of both mind and body.

Today the library houses the Keweenaw History Center and the park's Division of Museum, Archives, and Historical Services.