It was by far the longest suspension bridge to be built until that time.Fourteen years later,Robert Stephenson built the Britannia Bridge nearby to carry a new railway line that ran to the port of Holyhead.The longest suspension bridge in Britain is the Humber Bridge.Completed in 1981,it is 2,200 m(6,770 ft) long,with a central span of 1,410 m (4,700 ft).