From the workaday market town of RHAYADER, ten miles west of Llandrindod Wells, the B4518 heads southwest four miles to the gorgeous Elan Valley. It was here that the poet Shelley spent his honeymoon in buildings now submerged by the waters of the valley’s reservoirs, a nine-mile-long string of four lakes built between 1892 and 1903 to supply water to the rapidly growing industrial city of Birmingham, 75 miles east.
Frequent guided walks head off from the valley’s visitor centre, and a road tucks in along the first reservoir, Caban Coch, to the Garreg Ddu viaduct, where it winds along for four spectacular miles to the vast, rather chilling 1952 dam on Claerwen Reservoir. More remote and less popular than the Elan lakes, Claerwen is a good base for a serious walk from the far end of the dam across eight or so harsh but beautiful miles to the monastery of Strata Florida. Alternatively, you can follow the path that skirts around the northern shore of Claerwen to the lonely Teifi Pools, glacial lakes from which the River Teifi springs.
Back at the Garreg Ddu viaduct, a more popular road continues north along the long, glassy finger of Garreg Ddu reservoir, before doubling back on itself just below the awesome Pen-y-garreg dam and reservoir; if the dam is overflowing, the vast wall of foaming water is mesmerizing. At the top of Pen-y-garreg lake, it’s possible to drive over the final dam on the system, at Craig Goch. Thanks to its gracious curve, elegant Edwardian arches and neat little green cupola, this is the most photographed of all the dams.
Offa’s Dyke has provided a potent symbol of Welsh–English antipathy ever since it was created in the eighth century as a demarcation line by King Offa of Mercia, ruler of central England. George Borrow, in his classic book Wild Wales, notes that, once, “It was customary for the English to cut off the ears of every Welshman who was found to the east of the dyke, and for the Welsh to hang every Englishman whom they found to the west of it”.
The earthwork – up to 20ft high and 60ft wide – made use of natural boundaries like rivers in its run north to south, and is best seen in the sections near Knighton. Today’s England–Wales border crosses the dyke many times, although the basic boundary has changed little since Offa’s day. A glorious, 177-mile long-distance footpath runs the length of the dyke from Prestatyn in the north to Chepstow, and is one of the most rewarding walks in Britain.