Crossing the Pontcysyllte Aqueduct, a UNESCO World Heritage Site in Northeast Wales

The cast iron and masonry work on the Pontcysyllte Aqueduct in Wales are more than 200 years old. (photo credit: Katherine Rodeghier c 2013)

The cast iron and masonry work on the Pontcysyllte Aqueduct in Wales are more than 200 years old. (photo credit: Katherine Rodeghier c 2013)

From my vantage point in the field below, the structure rising from the riverbed looks like a bridge—a magnificent one, certainly, with graceful 200-year-old stone and iron arches. But wait a minute and an incongruous sight appears: A boat slowly making its way across the span, barely keeping pace with pedestrians walking alongside it.

Barges and narrow boats cross the "stream in the sky." (photo credit: Katherine Rodeghier c 2013)

Barges and narrow boats cross the “stream in the sky.” (photo credit: Katherine Rodeghier c 2013)

How can a vessel that floats on water cross a bridge 126 feet above a river? Simple; it’s navigating “the stream in the sky,” nickname for the Pontcysyllte Aqueductm, which links waterways in Wales.

In the 19th Century it was used for shipping, in the 21st it’s an attraction for leisure travelers—albeit a hair-raising one—who cross the aqueduct on foot or by barge.

Largest Aqueduct in Britain a Feat of Engineering

Constructed from 1795 to 1805, the aqueduct was built to carry the Llangollen Canal across the River Dee and serve as a linchpin in a network of waterways for the movement of cargo, such as Welsh slate, coal, iron ore, bricks and lime.

Designed by Thomas Telford, the leading civil engineer of the day, and canal engineer William Jessop, it stretches 1,007 feet across the river valley, making it the longest and highest aqueduct in Britain. It joined UNESCO’s list of World Heritage sites in 2009.

In Your Bucket Because . . .

  • You want the eerie feeling of being suspended in the sky.
  • You want to add to your list of visits to UNESCO World Heritage Sites.
  • Good for history and engineering buffs.

Considering the materials in use at the time, it’s an engineering marvel. The mortar in its 18 hollow masonry piers was made with a mixture of oxen blood, lime and water. The joints in the cast-iron trough through which the canal flows were sealed with white lead mixed with Welsh flannel and bits of iron from waste borings.


The aqueduct measures 11 feet wide with a walkway along one side of the trough, originally used as a towpath for the horses that pulled the barges. Every five years the five-foot deep trough is drained for cleaning and maintenance by pulling a plug near its center. It takes more the two hours to empty the aqueduct’s nearly 400,000 gallons of canal water into the river below.

The aqueduct joins the towns of Trevor and Froncysyllte in what was once Cysyllte Township. In the Welsh language, the name Pontcysyllte translates as Cysyllte Bridge.

Aqueduct Became Tourist Attraction with Canal Excursions

The aqueduct’s success in shipping was short-lived, thanks to the building of railroads that could move goods quicker and cheaper. With the opening of the Llangollen Railway in 1865 the canal company began a decline into bankruptcy. The last commercial barge passed over the aqueduct in 1901, less than a century after it was completed.

A narrow boat barely fits into the trough of the aqueduct, which is completely open on one side. (photo credit: Katherine Rodeghier c 2013)

A narrow boat barely fits into the trough of the aqueduct, which is completely open on one side. (photo credit: Katherine Rodeghier c 2013)

But leisure travelers of the Victorian age soon discovered the pleasures of cruising the canal. The Llangollen Wharf pleasure boat company began offering horse-drawn canal excursions in 1884, a practice it continues today, though excursions crossing the aqueduct use motorized barges. Barges and narrow boats also can be rented for weekend or week-long holidays on the canal through UK barge companies.

Navigating the aqueduct is not for the faint of heart, however. Pedestrians can stroll across on a paved walkway with the trough of the aqueduct on one side and a chest-high railing on the other to offer a barrier from the 126-foot drop below. No such barrier exists for boaters since the aqueduct is completely open on the west side. In fact, the lip of the trough is only six to eight inches above the waterline, so passengers sitting inside can’t see the edge and have the unsettling feeling of floating in midair.

A bit of advice: Don’t look down.

Practicalities

Getting there: South of Trevor in Wrexham County, Wales.

Information: Pontcysyllte Aqueduct or stop by the visitor centre in Trevor Basin.

Barge excursions: Llangollen Wharf and Jones the Boat offer short excursions on the canal and aqueduct.

Barge rentals: Among the companies renting narrow boats and barges on the Llangollen Canal are Canalia UK Boating Holidays and UK Barge Hire.

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