The canal boat drifted gently across the sky, 40 metres above the ground. Two men in a canoe followed. They were wearing lifejackets, although parachutes might have been more appropriate.
There is, it is safe to say, nowhere else in the world that you can float your boat so far off the ground as on this bit of the Llangollen canal, on Thomas Telford’s masterpiece, the Pontcysyllte aqueduct. It is a 307-metre long cast-iron trough perched on 18 stone arches that stride across the Dee valley in north Wales, a world heritage site that justifies its listing by being a genuine marvel of the Industrial Revolution.
And there is a lot more. This walk has numerous permutations, plus some combinations with the Offa’s Dyke Path, but I will assume a five-mile walk, a pub lunch, then a walk back along the same route. It’s so good, you will happily do it again.
We start to the south of the small town of Chirk, where the Llangollen canal comes curving in from the east, heading for the hills. Park by the canal (there’s a railway station in Chirk too) and set off north along the towpath. You are about to experience a number of engineering marvels and the opening salvo comes immediately with a 216-metre-long aqueduct that spans the River Ceiriog and valley.
In 1793 Thomas Telford was a respected architect in Shrewsbury, but his work in joining the rivers Severn, Dee and Mersey by canal would catapult him into the super-league of civil engineers, a realm he would dominate until the flamboyant young upstart Brunel eclipsed him.
The towpath is the best place to inspect Telford’s creation, a giant piece of Georgian plumbing consisting of an elongated cast-iron bath wide enough for a canal boat to be pulled along it by a horse 21 metres above the valley. No sooner is this finished than you enter the next marvel: the Chirk tunnel, a 420-metre unlit hole that burrows under the hill.
It is not the longest canal tunnel in Britain, but it is the longest you can safely walk. Be warned, it does get very dark in the middle – Wilf, my terrier, was not at all keen – but you can always see both ends, and there is a sturdy handrail.
Two centuries after their creation, these engineering wonders are well bedded into the landscape, but when they were built, they caused massive upheaval: lime kilns, brickworks, docks and boats had to be constructed.
Telford seems to have been happy to take all the credit, but the truth was that many others were involved. The towpath curves through a second, shorter tunnel before it crosses an earlier, even more ambitious feat of engineering, Offa’s Dyke, which is signposted.
Look out for the line of trees following a low embankment that drops down to meet the canal on the far side from the towpath. We know why Telford built the canal – to transport limestone and iron ore – but the purpose of King Offa’s equally massive project remains a mystery.
At Froncysyllte there is a small bridge and there is now a towpath on both sides as you approach the climax: Pontcysyllte (pronounced Pont-cuss-uch-tay). After the opening of the first canal, the Bridgewater, in 1761, aqueducts had been seen as desirable, but impossible. The consensus was that the weight of water would destabilise any structure beneath. Then in 1793, Benjamin Outram devised and built a short canal aqueduct using cast iron.
Telford followed suit. At Pontcysyllte, he made the 18 viaduct arches hollow to save weight, then mixed ox blood into the cement to add strength. The result is something both sturdy and graceful. It’s also vertiginously high and quite narrow: if you think canal walks are generally low-key and unadventurous, you will reconsider after this.
At the north end of the aqueduct, there is a choice. Sturdy walkers can continue, heading up the Offa’s Dyke trail along the spectacular Eglwyseg escarpment, well known to botanists for its unique species of tree, the Llangollen Whitebeam, not discovered until the 1950s. After three miles, there is an opportunity to turn left down to Castell Dinas Bran, an iron age hillfort with 13th-century ruins too, then into Llangollen.
If there’s time, visit Plas Newydd cottage, a gothic fantasy house created by Eleanor Butler and Sarah Ponsonby in Regency times, their relationship reputedly an inspiration to Anne Lister – “Gentleman Jack”– who came to visit, as did Byron, Shelley and the Duke of Wellington. From here, head back to the towpath and walk east back along the canal.
Alternatively, when you have crossed the aqueduct, follow the B5434 road down to the River Dee, where the 17th-century stone Cysylltau bridge gives a great view of the aqueduct. Continue up the road and turn right at the top for the Aqueduct Inn.
Google map of the route
Start Aqueduct Inn or the car park below
Distance 10 miles but easily adapted to be shorter, or longer
Time 5 hours
Total ascent 30 metres
Difficulty An easy route to follow. Take a torch for the tunnels.
Construction of the aqueduct was, no doubt, a thirsty business and after a day’s work the builders would step up the hill to the nearest establishment. There had been an inn on the spot for a long time, but a new name, The Aqueduct, was soon adopted. Nick Edwards and partner Teresa bought the place in 2016 and have finally (after an extended pandemic pause), refurbished it, bringing in an uncluttered yet cosy atmosphere.
The pub can be spotted a long way away by the addition of a spectacular mural artwork by canalboat artist Alan Baillie on the east-facing gable end. Whether Telford himself enjoyed a pint of Three Tuns in the bar is unknown, but in 1995 Luciano Pavarotti did visit while attending the nearby Eisteddfod. On entering, he heard the Froncysyllte Choir practising in the next bar and famously joined in. It’s that sort of place: friendly and relaxed.
There’s a terrace too, overlooking the canal and aqueduct. Food always includes vegetarian options and sharing plates. The steaks are from Welsh Black cattle reared in the hills around the village.
The pub is on Facebook
Where to stay
The Aqueduct Inn will be opening three new upstairs bedrooms in spring next year, the pick of which faces north across the Dee valley to the aqueduct. With oak beams and sills, stone features and lemon-yellow walls, the rooms will have a fresh light atmosphere and smart new shower rooms.
For those walking on up the Offa’s Dyke path, the Llangollen Hostel has cheerful, simple rooms from £43 a night, plus lots of books, games and a piano in the lounge. Visitors can make their own breakfast in the kitchen.
• This article was amended on 8 November 2022. An earlier version incorrectly described the Pontcysyllte aqueduct as “Victorian plumbing”; it was finished in 1805, which makes it a Georgian structure.