The preeminent Georgian engineer Thomas Telford (1757–1834) built the Pontcysyllte Aqueduct in 1805 to carry the canal over the River Dee. At 307m long, 3.6m wide, 1.7m deep and 38m high, it is the most spectacular piece of engineering on the entire UK canal system and the highest canal aqueduct ever built. In recognition of this, the aqueduct and an 11-mile stretch of the canal have been declared a Unesco World Heritage Site. FYI, it's pronounced 'pont-kus-sulth-teh'.

　　In the 18th century the horse-drawn canal barge was the most efficient way of hauling goods over long distances, but, with the advent of the railway, most of them fell into disrepair. The Llangollen Canal fared better than most because it was used for many more years to carry drinking water from the River Dee to the Hurleston Reservoir in Cheshire. Today it's again in use, carrying visitors up and down the Vale of Llangollen. In addition, the old towpaths offer miles of peaceful, traffic-free walking.

　　Telford's goal was to connect up the haulage routes between the Rivers Dee, Severn and Mersey. To collect water for the canal from the Dee, he also designed an elegant curving weir called Horseshoe Falls. The adjacent riverbank is a tranquil picnic spot.

　　Blue-badge guides run tours from near the aqueduct visitor centre, while canal boats offer trips along the 'stream in the sky' from the nearby quay and from Llangollen wharf. Otherwise you can simply stroll across, free of charge. Whichever way you choose, you'll need a head for heights.

　　Horseshoe Falls is about 2 miles west of Llangollen (take the A5 west and after about 1.5 miles turn right across the river), while the aqueduct is 4 miles east, near the village of Trevor (on the A539 Ruabon road). Both are easily reached by the canal towpath, if you're in no hurry.