I went with my grandparents to Pontcysyllte in August 2013, having also visited around six years earlier - before it was inscribed in in 2009.

Pontcysyllte Aqueduct and Canal is deemed to be worthy of recognition because it is an early example of the ingenuity of the engineers and architects of the Industrial Revolution. Wales’s hilly terrain does not lend itself to the needs of canals, yet this section traverses the countryside without resorting to locks.

Conceived of and overseen by Thomas Telford, construction began in 1795 and was completed 10 years later. The bridge has withstood the test of time, with even the cast iron trough being the original one put in by Telford more than two centuries ago. The mortar is apparently made from lime, water and ox blood!

In addition to Pontcysyllte, I went to see the less famous Chirk aqueduct (also part of the inscription). It was completed four years earlier than Pontcysyllte and is now flanked by a railway bridge alongside it. From the aqueduct the canal goes quickly into a tunnel, which provides a clear reminder of just how undulous the terrain is. The landscape, formerly covered in foundries, brickworks and lime kilns, was described in Victorian times as “a vision of hell”. Nowadays that description couldn’t be further from the truth.