development projects planned in the vicinity of the Pontcysyllte (United Kingdom) property. The State Party replied with a detailed memorandum with a document and maps attached (60 pages). The analysis of No 1303 this documentation is included in the present evaluation. Date of ICOMOS approval of this report: 10 March 2009 Official name as proposed by the State Party: Pontcysyllte Aqueduct 2. THE PROPERTY and Canal Description Locations: Wrexham Borough and The Pontcysyllte Canal is in north-eastern Wales, 65km Denbighshire (Wales), south of Liverpool, not far from Chester. Municipality of Oswestry, The nominated property consists of the whole length of the County of Shropshire canal and its banks; 17km of its 18 km length is in Wales (England), United Kingdom. and 1km in England. It includes the towpath and adjacent buildings directly connected with its history. At three Brief description: points the property is enlarged in order to include an expanse of land associated with a civil-engineering Pontcysyllte Canal, in the north-east of Wales, is an structure or a stretch of water, forming a typical landscape. example of a waterway which typifies land-use planning This is the case at the water intake and weir at Horseshoe during the Industrial Revolution in Great Britain. Built Falls, the Pontcysyllte Aqueduct, and the Chirk Aqueduct. from 1795 to 1808, the canal presented great geographical difficulties, which civil engineer Thomas Telford resolved The Pontcysyllte Canal is a narrow waterway, 8–9m wide in particular by the construction of a very large aqueduct and 1.5m deep, permitting the passage of barges c 2m wide with cast-iron arches supported by masonry piers. This carrying loads of around 30 tonnes, which at the time was a type of construction was totally new, both in its iron standard type in Great Britain. The nominated property, the architecture and its monumental dimensions. Furthermore, Pontcysyllte Canal, forms the end of the western branch of Pontcysyllte illustrates the mastery of canal civil the Ellesmere Canal. engineering in a hilly zone by the British engineers of the The ensemble constitutes a single reach, i.e. there are no time. locks. Avoiding the need for locks called for substantial civil-engineering works in uneven terrain – two aqueducts, Category of property: two tunnels, trenches, large cuts and fills, lining, etc. It passes through rich coal deposits and limestone quarries, In terms of categories of cultural properties, as defined in one of the reasons why the canal was dug. Article 1 of the World Heritage Convention of 1972, this is a group of buildings. The hydraulic point of departure of the canal is the water intake at Horseshoe Falls on the River Dee, starting from the weir reservoir (km 0). From there, the canal runs west 1. BASIC DATA along the northern side of the valley. Substantial rock cuts Included in the Tentative List: 21 June 1999 were often necessary on the upper side, in some cases more than 1km long, together on the lower side with masonry International Assistance from the World Heritage Fund for structures or large rubble embankments. The canal passes preparing the Nomination: None the town of Llangollen (km 3), where there is a port basin. Date received by After running for c 10km from west to east, the waterway the World Heritage Centre: 11 January 2008 reaches Trevor, where there is a large independent basin, Background: This is a new nomination. of around 400m at right-angles to a loop in the canal. Consultations: ICOMOS has consulted TICCIH (The The waterway then turns south and has to cross the River International Committee for the Conservation of the Dee, the wide valley of which is below the level of the Industrial Heritage). canal. Telford, the engineer, had the task of designing the impressive Pontcysyllte Aqueduct (km 10.2). The Literature consulted (selection): difference in water levels is 38.4m and the length of the ICOMOS/TICCIH, The International Canal Monuments List, aqueduct over 300m. It has to support a large mass of Paris, 1996. water while ensuring a high degree of watertightness. Telford designed a bridge with nineteen cast-iron arches Bergeron, L. (ed.), ‘Papers from the Pontcysyllte International supported by tall masonry piers. The metal arch is made of Canal Conference’; Patrimoine de l’industrie / Industrial Patrimony, 17, 2007. cast-iron voussoirs, and the waterway channel consists of abutting cast-iron plates reinforced by an external metal Technical Evaluation Mission: 24–26 September 2008 structure. The whole construction is far lighter than it would have been had stone arches been used, which made Additional information requested and received from the possible the use of conventional but particularly slim piers, State Party: ICOMOS sent a letter to the State Party on 10 giving a light and elegant overall impression, which December 2008 asking it to provide a summary table in contemporaries found very impressive. When completed in which the component parts of the property are defined in a homogeneous way, together with information about any 212 1805 it was unique, both in terms of its technical and architect who had a remarkable ability for finding new performances and its cast-iron superstructure. technical solutions to building and civil-engineering problems. He was already well known when he was The Trevor basin and its buildings, the Pontcysyllte engaged and had just undertaken the construction of Aqueduct, which constitutes the outstanding monumental several cast-iron bridges, such as the Longdon aqueduct to and technical feature, and the landscapes both upstream cross the Severn. He also proposed a cast-iron bridge to and downstream of the crossing of the River Dee form the cross the Thames. In the same region he was also central area of the property. employed to build the road from London to Dublin. The exit from the aqueduct is via a large fill embankment. The aqueduct over the Ceiriog at Chirk was the first Many difficulties then have to be solved to reach the structure to be planned, in 1795, by Jessop and Telford. Ceiriog valley. Again there are cut-and-fill sections, with After considerable discussion a stone structure was retaining walls, the Whitehouse tunnel (km 13.1) which is c preferred. Shortly afterwards, when the crossing of the Dee 120m long, and the Chirk tunnel (km 15.6) c 400m long. came up for consideration, the conditions were different. The tunnels are strengthened by brick arches and have The valley was wider and deeper, and a conventional masonry portals. aqueduct would therefore have been be very costly; The Canal crosses the Ceiriog by the impressive Chirk furthermore, cast-iron bridges were beginning to prove Aqueduct (km 16.2). Slightly older than the Pontcysyllte their qualities. The cast-iron bridge solution proposed by aqueduct, it is made of masonry, stands more than 20m Telford was chosen and construction work began under his above the river, and has ten arches. At the time of its supervision. The canal up to Trevor was opened on 26 completion in 1801 it was the highest and largest canal November 1805. The part which extends the canal to aqueduct ever built. Horseshoe Falls was completed in 1808. The nominated property ends shortly afterwards, at Gledrid As soon as it had been built the Pontcysyllte aqueduct Bridge (km 16.7), but the waterway continues under the became famous for its highly innovative technical and name of the Ellesmere Canal. architectural boldness. When completed it was recognised as an outstanding success, eliciting praise from engineers The canal infrastructures include many small masonry and inspiring Romantic artists. After the end of the bridges that allow the passage of streams, and weirs to Napoleonic wars several foreign engineers and scholars control the canal level. came to visit the aqueduct. The property includes various basins and wharves linked to The Pontcysyllte aqueduct made Thomas Telford famous. mining and commercial activities and a series of service He was recognised in his lifetime as the greatest builder of buildings along the canal. The buildings are often iron bridges and canals of his time. He became the first associated with the exploitation of coal mines and president of the Institution of Civil Engineers in London in limestone quarries close to the waterway. The canal is also 1825. Telford and his Pontcysyllte aqueduct had an crossed by a number of bridges, some of which are important influence in the international development of contemporary with the construction of the canal and are in canals at the beginning of the 19th century in Great Britain, harmony with it; two are small lift-bridges. The others are Europe and North America. Telford participated in the from are a later period, in various styles. The largest is the construction of other very well known canals, such as the railway viaduct parallel and adjacent to the Chirk Caledonian Canal in Scotland and the Göta Canal in Aqueduct, built by Brunel. All the technical and Sweden. architectural elements of the property are listed in the dossier and their state of repair is assessed. The economic influence of the canal for the region was considerable during the first half of the 19th century, A very large buffer zone surrounds the property, enabling the rapid development of coal extraction, metal corresponding to the crests of the hills visible from the working, limestone quarries, and the production of lime. canal on both sides of the valley. The slate quarries of the Welsh mountains and agriculture also benefited from the canal. By 1815 the substantial investments it had required had been repaid and the canal History and development became a highly profitable business. Its direct link with a vast network of canals to the Mersey, through the In order to link Chester and the Mersey estuary to the Midlands, and as far as London, greatly encouraged the use Severn and the Midlands canal network, the Ellesmere of the canal.