Pontcysyllte Aqueduct and Canal World Heritage Site Pontcysyllte Aqueduct and Canal was designated a site of Outstanding Universal Value and placed on the World Heritage List on 27th June, 2009. The 11 mile/18 kilometre World Heritage Site starts at Gledrid Bridge near Chirk and extends to the Horseshoe Falls above Llangollen, where water is taken from the River Dee to feed the canal system. It is the first World Heritage Site in the United Kingdom to straddle two Countries, Wales and England. The site was built between 1795 and 1808 and represents the work of two outstanding figures, Thomas Telford and William Jessop. Pontcysyllte Aqueduct is the highest navigable aqueduct ever built and is recognised internationally as a masterpiece of civil engineering.