“One of the pleasantest things in the world is going a journey,” wrote the essayist, William Hazlitt, “but I like to go by myself.”

Hazlitt was 19 when he first met Samuel Taylor Coleridge, in January 1798. The poet was impressed by the earnest youth and invited him to visit Nether Stowey in Somerset, where he was working with William Wordsworth on what would become the Lyrical Ballads, the founding text of English Romanticism.

In preparation for this illustrious visit, the young Hazlitt decided to initiate himself “in the mysteries of natural scenery” and set off, on his 20th birthday (April 10th) to walk around the picturesque Vale of Llangollen.

“That valley was to me (in a manner) the cradle of a new existence,” he wrote later. “How proud, how glad I was, to walk along the high road that commanded the delicious prospect, repeating the lines which I have just quoted from Mr Coleridge’s poems!”

This 21-mile circular route follows Hazlitt’s footsteps around Llangollen, and is dotted with scenic “ruins, aqueducts, [and] pictures”. I walked it over two days with my 1970 Penguin edition of his Selected Writings for company: I started and finished at Chirk railway station and stayed overnight at Llangollen.

A few yards west of the Chirk station, drop down to the canal towpath and walk away from Chirk Tunnel through soaring beech woods. The Llangollen Canal is the most popular cruising canal in the country, with puttering narrowboats nosing along at less than walking pace.

Pass Chirk Marina on the left and creep through the Whitehouses Tunnel. When the canal curves left you’ll start to glimpse the valley far below, as you approach the Pontcysyllte Aqueduct.

This extraordinary structure was under construction when Hazlitt walked past in 1798. At 38 metres, it is now the highest navigable aqueduct in the world, and the oldest in Britain.

It was designed by the engineer Thomas Telford as part of the Ellesmere Canal, an ambitious project to connect the River Severn at Shrewsbury with the River Mersey at Ellesmere Port. The scheme was abandoned soon after the aqueduct was completed, but Telford’s feat of engineering is nonetheless staggering: his canal drops a mere 50 centimetres over the course of 11 miles.

To honour his achievement, the entire area was declared a world heritage site in 2009.

On the far side, cross the winding hole over the footbridge and follow the branch canal west, towards Llangollen. Keep to the righthand side of the canal and, beside the second bridge, turn right on to the Offa’s Dyke Path.

The path squeezes beneath a dismantled railway line, and wiggles away from the village of Trevor before heading up through the atmospheric pine woods surrounding the 18th-century Trevor Hall.

After a long, well signposted climb between the trees, you burst into the open and there’s a spectacular view, with the dramatic Castell Dinas Brândirectly ahead.

“You come all at once upon the valley,” wrote Hazlitt, “which opens like an amphitheatre, broad, barren hills rising in majestic state on either side.”

Follow the road towards the castle, with the sheer Eglwyseg escarpment to the right, until you can turn left and follow the steep steps up to the ruins.

Known locally as Crow Castle, this once mighty palace was built in the 1260s by Gruffudd II ap Madoc, Prince of Powys Fadog (Lower Powys), on the site of an iron age hill fort. It survived only a few years: in 1277 it was besieged by the English and the castle’s Welsh defenders burned it to the ground before fleeing. Brân, which means ‘“crow”, is the name of a giant of Welsh legend: Brân the Blessed was a supernatural prince, whose decapitated, talking head is said to have protected the realm from invasion. He is the Fisher King of Arthurian legend, and Dinas Brân may be the location of Castle Corbenic, home of the Holy Grail.

Descend on the other side of the hill and follow the path until you get to a three-way signpost. Here there is a choice: turn left and shortcut straight to Llangollen, or right along a path that skirts the edge of the hill.

Follow this path as it drops past a wooden crow and take the left turn signed to Dinbren. Turn right when you hit the road and right again on the road signed to World’s End. Turn immediately left on to the Clwydian Way.

After passing some rudimentary red seats this pleasant grassy path slopes down to a signpost. Turn hard left, signed to Valley Crucis Abbey.

Follow the path across a large open field, looking out for an almost invisible right-hand turning, over a metal stile, signed to Velvet Hill.

Take this precipitous path until it reaches a road. Here it’s worth a short detour right to inspect the Pillar of Eliseg.