In some occurances, historic buildings, structures and sites are not able to be saved, however, that does not mean that historic preservation methods cannot be implemented. Documenting a building, structure and site through a variety of mapping and image-collecting methods give the future generations reference to the historic built environment. Before demolition, relocation or high impacts to the architectural integrity, Calhoun Preservation is prepared to document the building to ensure that key information is collected about its appearance, construction and history. Reports prepared for the Historic American Buildings Survey or the Historic American Engineering Record are archived in the Library of Congress. Other documentation reports are maintained by the State Historic Preservation Office.