On back: "SAN FRANCISCO-OAKLAND BAY BRIDGE; Walter G. Swanson; 500 Sansome St. - GA rfield 1415. File 900.11 B-12/AA. JUST A PIECE OF TOWER BRACING - The cross-shaped bracing in the center of this picture, weighing 50 tons, is just one piece of cross bracing for a San Francisco-Oakland Bay Bridge tower. This little bit of bracing is approximately the width of Market Street. 2-9-34".