Constructed with funds from two sources, 55% from Crane family funds and 45% from the U.S. Public Works Administration, this 1939 addition was dedicated as the Albert Crane Memorial Wing in 1952.
Designed by Paul A. and Carroll Coletti, Quincy and Boston architects, it is Richardson Romanesque modified to permit better natural lighting and retains the turret and eyebrow windows.
The exterior is of granite and brownstone to match the color and texture of the same materials in the 1882 building. The roof of red slate continues the harmony of the two buildings. The two carved brownstone bas reliefs flanking the main entrance symbolize Quincy's granite and shipbuilding industries. In the gable end of the street elevation is a crane to commemorate the generosity of the Crane family.
Rear elevations are of glazed brick specially made with quartz and mica spots to match the granite of both buildings.
The interior woodwork is of native pine and the furniture, specially designed by the architects, is of maple.