The Maine Historical Society Library, built in 1907, was designed by architect Alexander W. Longfellow, nephew of the poet Henry Wadsworth Longfellow. The building also served as the headquarters for Maine Historical Society's administration until the 1990s, when the Society acquired an adjacent building at 489 Congress Street.

The reading room, pictured here, highlights the iron stacks (seen in background). This structural design was considered a state-of-the-art at the turn of the 19th to the 20th century. Between 2007 and 2009, the library underwent an extensive restoration and renovation project which removed the central staircase (pictured) although the iron stacks remained intact.