Iron Bridge Introduction: The arched structure of the main body of the Iron Bridge spans one hundred feet, is 52 feet high and 18 feet wide. It is entirely cast from iron and weighs hundreds of tons. It has a classical symmetry of 18th century architecture. and elegance. A few years after the iron bridge was built, there was a major flood here. After the flood, all the stone bridges on the Severn River were destroyed, but the iron bridge remained intact. From then on, the iron bridge became famous, and the cast iron company that built the iron bridge received a steady stream of orders.