The Pontcysyllte Aqueduct, a UNESCO World Heritage Site, is a 19th-century engineering marvel that carries the Llangollen Canal over the River Dee in north-east Wales. This massive structure, designed by Thomas Telford, is 336 meters long and 38 meters high, with 19 pillars supporting its 1.5-meter diameter cast-iron tubes. The aqueduct's most striking feature is its central section, which forms a waterfall-like cascade as the canal water flows over the edge, creating a picturesque scene.