Pontcysyllte Aqueduct

Tuesday, 7th July 2009 by

This is the Pontcysyllte Aqueduct, or to give it its full Welsh name, Traphont Ddŵr Pontcysyllte1, which carries the Llangollen Canal over the valley of the River Dee in north east Wales, and which has recently been recognised as one of the most important engineering accomplishments of all time.

Completed over 200 years ago, this stunningly beautiful engineering masterpiece was designed by everyone’s favourite2 civil engineer Thomas Telford (1757 – 1834), and to this day it remains the longest and highest aqueduct in the UK.

Despite scepticism at the time (this was the late 1700s after all), Telford was convinced he could build a cast iron trough to carry the canal over the massive 307 metre span of the valley. After all, he had seen his methods succeed at Longdon-on-Tern, where he had designed the world’s first cast iron navigable aqueduct.

Originally constructed as part of the now long-abandoned Shrewsbury Canal, today the Longdon-on-Tern aqueduct still sits astride the River Tern, and is not only Grade I listed but is also a scheduled ancient monument.

Despite this previous experience, the Pontcysyllte Aqueduct is truly a testament to Telford’s genius. The cast iron trough he designed soars 38 metres above the valley floor, regularly carrying narrowboats safely3 over the valley.

In ultimate recognition of its importance, on the 27th of June 2009, the Pontcysyllte Aqueduct became a UNESCO World Heritage Site, joining a list of nearly 900 other places of great cultural or physical significance that includes such treasures as the Taj Mahal, the Great Wall of China, and Stonehenge.

Thanks to the ever on-the-ball Jonathan Rawle. See the Wikipedia links in this article for more info, or explore Wikipedia’s list of works by Thomas Telford.

  1. How glad am I that I don’t have to try and say that out loud? 

  2. Well he’s everyone’s favourite where I live, as we’re very proud of Scotland’s most famous bridge-building son.4 

  3. Assuming you don’t fall off of course – there is no guard rail at all on the canal side

  4. Granted, you may be more familiar with the work of John Rennie or Sir William Arrol, but surely neither has a name as widely known as Telford’s?