original american machine age art deco style ornamental cast bronze "chicago" pattern residential or possibly commercial building office door backplate likely fabricated by lockwood or the sargent hardware company. the oversized doorknob backplate contains a unique top and bottom ziggurat motif, along with a staggered or stepped design running vertically against the outer edges. the surface patina is mostly uniform throughout. the escutcheon contains four screw holes for mounting purposes. measures 9 1/2 x 2 1/2 inches.