Statement of Outstanding Universal Value
This was approved in 2009 by the World Heritage Committee in Seville
The Pontcysyllte Canal is a remarkable example of the construction of a human-engineered waterway in a difficult geographical environment, at the end of the 18th century and the start of the 19th century. It required extensive and boldly conceived civil engineering works. The Pontcysyllte Aqueduct is a pioneering masterpiece of engineering and monumental architecture by the famous civil engineer Thomas Telford. It was constructed using metal arches supported by tall, slender masonry piers. The Pontcysyllte Aqueduct and Canal are early and outstanding examples of the innovations brought about by the Industrial Revolution in Britain, where they made decisive development in transport capacities possible. They bear witness to very substantial international interchanges and influences in the fields of inland waterways, civil engineering, land-use planning, and the application of iron in structural design.
Criterion (i): The Pontcysyllte Aqueduct is a highly innovative monumental civil engineering structure, made using metal arches supported by high, slender masonry piers. It is the first great masterpiece of the civil engineer Thomas Telford and formed the basis of his outstanding international reputation. It bears witness to the production capacities of the British ironmaking industry, which were unique at that time.
Criterion (ii): The intensive construction of canals in Great Britain, from the second half of the 18th century onwards, and that of the Pontcysyllte Canal in particular in a difficult region, bear witness to considerable technical interchanges and decisive progress in the design and construction of artificial waterways.
Criterion (iv): The Pontcysyllte Canal and its civil engineering structures bear witness to a crucial stage in the development of heavy cargo transport in order to further the Industrial Revolution. They are outstanding representatives of its new technical and monumental possibilities.
Integrity and Authenticity
The integrity of the waterway has been maintained in hydraulic and civil-engineering structures that have remained in their original form. However, the historic embankments, made of rubble, have raised significant problems of stability and waterproofing, particularly in the second half of the 20th century. The repairs have involved the use of technical solutions that are different from the simple initial backfills, both for structural resistance and waterproofing: concrete, steel pilings, geotextiles, etc. From the point of view of integrity, these works have made it possible to maintain the hydraulic operation of the waterway and to conserve its overall morphological characteristics. The integrity of the landscapes and the buffer zone of the property contributes to the expression of the value of the property. The property has all the elements of integrity necessary for the expression of its value, as a major historic canal of the Industrial Revolution. The few structural changes that have been made to the two large aqueducts have remained secondary, contributing to maintaining the property in use. Changes in materials have remained restricted over the history of the property. During the 20th century repairs to masonry did not always use the original types of mortar or stone. The buildings associated with the canal and its immediate environment usually achieve a good degree of authenticity.
Management and protection requirements
The technical and monumental management by British Waterways is satisfactory. The management plan is acceptable; it clearly defines the objectives of conservation, but it would be improved by a unified approach to the preservation of the buffer zone and the drafting of a plan for tourism development and site interpretation.
World Heritage Site inscribed by the World Heritage Committee of UNESCO in 2009.