This series contains projects done by Cardwell as a historic preservation consultant, and historical architect working with the firm Hall, Goodhue, and Haisley. For many of these projects Cardwell worked for federal and municipal governmental offices, as well as private clients. Major projects include his work as a preservation consultant for the Department of Parks and Recreation, the Historic American Buildings Service, the National Trust for Historic Preservation, and the University of California, Berkeley. While some projects contain drawings and photographs, all project records contain manuscript materials.