Pont-y-Cysyllte aqueduct on the Ellesmere Canal where it passes through the Vale of Llangollen, Wales. The most notable of all the iron trough aqueducts in Britain. Built by Thomas Telford (1757-1834) Scottish civil engineer. Opened in 1805, it is 307 metres long, with 19 arches and is 30.7 metres above the river Dee. It cost ?47,018. Lithograph.