26th November 1805: Pontcysyllte Aqueduct, highest canal aqueduct in the world, opens in North Wales

Built to carry the Llangollen Canal across the River Dee, the Pontcysyllte Aqueduct is one of the most remarkable engineering achievements of the Industrial Revolution. At 307 meters in length and 38 meters in height, the aqueduct was the highest and longest of its kind. It provided a direct waterway link between the industrial towns of Shropshire and the Welsh coalfields, facilitating movement of goods and resources essential for industrial growth in the region.

Designed by Scottish civil engineer Thomas Telford, and overseen by William Jessop, construction began in 1795 and continued for ten years. The use of a cast-iron trough, supported by eighteen hollow sandstone pillars, meant the overall structure was both lighter and more durable than traditional stone aqueducts. The pre-cast iron pieces were assembled on site, with the joints made watertight using a mixture of Welsh flannel and lead.

The aqueduct opened to traffic on 26 November 1805 and transformed transport in the region by creating a direct route for the movement of coal, limestone, and other industrial materials. The Llangollen Canal became a major transportation artery, with the aqueduct serving as its most impressive and strategic crossing. Its successful design and construction also solidified Thomas Telford’s reputation as one of Britain’s leading engineers, influencing future projects throughout the country and beyond.

The Pontcysyllte Aqueduct continues to stand as an operational canal bridge, and was designated a UNESCO World Heritage Site in 2009 due to its historical significance and pioneering design.