The cast iron bridge built by Abraham Darby III in 1779 at Ironbridge, Shropshire.
Wrought iron is a commercial form of smelted iron (the other is cast iron), containing less than 0.3% carbon with 1 or 2% slag mixed with it. Originally it was made from ore in a forge, and later in a "puddling" furnace, where it never becomes molten. Wrought iron replaced bronze in Asia Minor (c. 2000 BC) at the beginning of the Iron Age. In the 19th century wrought iron began to be used in building construction, but was replaced by steel after the invention of the Bessemer process and open-hearth process. Although it has useful mechanical properties, little wrought iron is now manufactured. See also .