Copley Station is located directly beneath the Boston Public Library and served it and the surrounding environs.
The Library can be accessed through Copley Station. The entrance of the station leads down to the main subway platform. Going toward the back and hooking back around the subway cars take one to an open car containing a cooking station and connects to another care containing a chemistry station. A stairwell on the east side of the platform lead up to the actual library.
Copley station appears only in Fallout 4.