"The Keystone Bridge Company, founded in 1865 by Andrew Carnegie, was an important American bridge building company. It was one of the 28 companies absorbed into the American Bridge Company in 1900. The company advertised its services for building steel, wrought iron, wooden railway and road bridges. It held a patent for wrought iron bridges and also supplied wrought iron columns for buildings."@en . "1865Z"^^ . . "Keystone Bridge Company"@en . . . . . . .