Built by architects Thomas Telford and William Jessop in 1805, Pontcysyllte’s cast-iron aqueduct stands on 18 pillars at a height of 30 metres above the River Dee. Located on the Welsh-English border near the 18th century-road crossing at Pont Cysylltau, it is a navigable aqueduct that carries the Llangollen Canal across the river in north-east…