Pontcysyllte Aqueduct: Abseiling workers clean-up landmark

The cast iron trough holds 1.5m litres of water from Llangollen Canal

Contractors with a head for heights have begun clean-up work on Wrexham's towering Pontcysyllte Aqueduct.

Workers wearing harnesses are abseiling down Britain's biggest aqueduct to carry out maintenance which includes removing vegetation from the structure.

Constructed under the instruction of Thomas Telford between 1796 and 1805, the aqueduct stands 126ft (36m) high.

The cast iron trough holds 1.5m litres of water from Llangollen Canal and is supported by 18 piers and 19 arches.

Going down... a contractor prepares to go down the side of the aqueduct

The aqueduct and canal were made a world heritage site in 2009.

The work by the Canal & River Trust is part of an £80,000 project to protect historic structures along the Llangollen and Montgomery canals this winter, including Montgomery and Chirk aqueducts, and Ellesmere, Chirk and Whitehouse tunnels.