One of the canal masterpieces is right on our doorstep yet many people take their boats across it or walk or ride on the towpath without realising what is beneath them.When the navvies building the canal reached the western end of Hirst Wood, just before Dowley Gap, they had the problem of getting across the River Aire and the tail-race from New Hirst Mill. One of the country’s leading engineers, James Brindley (pictured), solved the problem with Seven-Arches aqueduct, . Built by local stonemasons James Rhodes of Shipley, Jonathan Sykes of Oulton and Joseph Smith of Woodlesford, it carries the canal 30ft above the river. Beneath it, the structure is protected by pitched stones if the river floods.