Pontcysyllte Aqueduct was one of the wonders of its age and a pioneer in the use of cast iron as a building material. This structure is Britain’s longest and highest aqueduct. The aqueduct is commonly credited to Thomas Telford, who was overseer of works on the Ellesmere Canal project and claimed the credit decades later. Initially the aqueduct was ascribed to William Jessop, the canal’s engineer. He had earlier helped to found an ironworks in Derbyshire. The concept was probably developed by both men, aided by earlier aqueducts and an American engineer.
Envisaged as the central section of the Ellesmere Canal, it was originally intended to cross the Dee Valley at a much lower level, with a series of locks taking the canal down to an aqueduct 50 feet above the river Dee. However, Thomas Telford conceived the idea of carrying the canal across the valley at full height, in an iron trough mounted on a series of stone pillars and work began in 1795.
The eighteen sandstone pillars were quarried at Cefn Mawr and transported to the site, where it would have been cut and dressed. The pillars taper from 6.4 metres at the base to 5.1 metres at the top. The ironwork for the trough was cast by William Hazeldine at his foundries in Shrewsbury and Cefn Mawr.
The canal was intended to continue northwards from Trevor basin but the hills which stood in the way, and the rapid growth of railways, put paid to the idea. The canal’s water supply was originally planned to flow along a trench from beyond Llangollen, but in the event this section was built almost entirely as a navigable canal.
During the Second World War, the London, Midland & Scottish Railway decided to close many of the canals it had inherited, but the Ellesmere Canal had become an important distributor of water. Today Pontcysyllte remains part of the system which takes drinking water to Hurleston reservoir, near Nantwich, Cheshire.
In the 1950s this part of the Ellesmere Canal was renamed the Llangollen Canal, reflecting its growing leisure use. In 2009 the Llangollen Canal was designated a United Nations World Heritage Site.
