Pontcysyllte Aqueduct, world heritage

The Pontcysyllte Aqueduct is a navigable aqueduct that carries the Llangollen Canal over the valley of the River Dee in Wrexham County Borough in north east Wales. Completed in 1805, it is the oldest and longest navigable aqueduct in Great Britain and the highest in the world, a Grade I Listed Building and a World Heritage Site. The viaduct carries a water passage for a single canal narrow boat as well as a towpath for pedestrians, and is now a popular tourist excursion; boat trips cross the viaduct and return.