very rare and highly collectible 19th century single-sided ornamental cast iron american bridge plaque. the deeply embossed shield would have been mounted to a pin or gusset-jointed girder on either end of the truss bridge. salvaged from a south side chicago bridge. the chicago bridge and iron works was established in 1889, when george and william wheelock agreed to merge their kansas city bridge and iron company with bridge builder horace horton. measures 13 x 8 inches.