Taking 10 years to build - the first stone was laid on July 25 1795 - Pontcysyllte Aqueduct is widely regarded as the best work of Thomas Telford and, in 2009 it became a World Heritage Site alongside the Great Wall of China.
The aqueduct is situated near to the Trevor Basin on Llangollen Canal at Froncysyllte, near Wrexham. It takes its name from a triple arched bridge a little further up the river and, literally translated, means 'the bridge that connects the river'. Llangollen Canal - for which Telford was the agent - is fed from the River Dee.
The aqueduct is built on one strata of rock, each pier being constructed of local stone and rising to a height of 116ft (35m). The support piers are tapered, measuring 27ft (8m) in width at the bottom and 17ft (5m) at the top. A total of 19 cast iron arches, each with a 45ft (13.6m) span support the bridgework. Mortar used in the construction comprised of lime, water and oxen blood.
The iron castings were produced at the Plaskynaston Foundry, near Wrexham, and each casting dovetails into the next. To seal the joints, Welsh flannel and lead were dipped in boiling sugar. The bridge section was made entirely from cast iron, the overall dimension of ironwork being 11ft (3.3m) wide, 5.25ft (1.6m) deep and 1,007ft (305m) long. Once constructed the trough was filled with water and left to stand for six months.
The bridge had cost some £45,000 to build and was opened on November 26 1805, in the presence of 8,000 people. The opening ceremony involved the passage of six boats across the aqueduct and back again, commencing on a cannon signal from the Royal Artillery on a platform below.
The first two boats carried the managing committee and their families, the third carried the band of the Shropshire Volunteers in full dress uniform, and the fourth carried the civil engineers. The last two boats carried a cargo of coal representing the first commercial use of the aqueduct.
A plaque on one of the piers reads: "The nobility and gentry of the adjacent counties having united their efforts with the great commercial interest of this country in creating an intercourse and union between England and North Wales. By navigable communication of the three rivers - Severn, Dee and Mersey, for the mutual benefit of agriculture and trade, caused the first stone of the aqueduct of Pontcysyllte to be laid, on the 25th July, 1795, when Richard Myddleton - MP of Chirk, one of the original patrons of the Ellesmere Canal [Llangollen Canal's former name] was Lord of the Manor and in the reign of our sovereign George III. When the Equity of the laws and security of property promoted the general welfare of the Nation, while the arts and sciences flourished by his patronage, and the conduct of civil life was improved by his example."
With thanks to British Waterways for the text & BBC Shropshire for the photo
