This 10-arch structure carries the Llangollen Canal over the Ceiriog Valley. It took several years to build. It opened in 1801, when boats began to transport goods from the basin at the north end. The canal was extended to Froncysyllte the following year.
The aqueduct, which crosses the Wales-England border, is part of the ambitious Ellesmere Canal route devised by canal engineer William Jessop. Construction was overseen by Thomas Telford. The canal crosses the Ceiriog and Dee valleys on high aqueducts to avoid inefficient flights of locks on both sides of each valley.
Although this aqueduct looks like a structure of stone and brick, an iron trough runs along the top to contain the canal water. This innovative use of iron was achieved with the help of master ironworker William Hazledine, who had opened a foundry near Plas Kynaston Hall. For the extension across the Dee, Pontcysyllte aqueduct was built with the canal in an iron trough alone, without supporting stone arches.
The water is periodically drained from both aqueducts for trough maintenance. The lower photo, courtesy of the Canal & River Trust archive, shows workers on Chirk aqueduct in 1954. Their tasks included applying a protective coating to the metal.
Alongside Chirk aqueduct stands the 16-arch viaduct of the Shrewsbury & Chester Railway, engineered by Henry Robertson. He enlarged Siambr Wen, alongside the canal in Llangollen, as a residence for his four siblings.
The Board of Trade inspector who checked the railway before it opened in 1848 was impressed by the viaduct but complained that it was too close to the “celebrity” aqueduct! He thought their proximity spoiled the visual effect of both structures.
Today the Llangollen Canal is a popular leisure route, looked after by the charity Glandwr Cymru the Canal & River Trust in Wales. The canal is a UNESCO World Heritage Site.