It's an easy stroll down here from Pen-y-Beacon circle (28.4.2011). On the way, I notice a couple of low stones protruding from the turf on the east side of the road. They may be natural, but they are reminiscent of the low stones used in the circle.
Twyn-y-Beddau ("The Mound of Graves") is a prominent barrow. It has been - and continues to be - ill-treated, but still stands 2m tall. From bits of stonework protruding through the turf it seems to be more of a cairn than its grassy appearance might suggest. It unfortunately seems to be in use an impromptu golf tee, judging by the number of plastic tees scattered around. It has also been damaged by the road that passes very close to (through) its west side. The worst damage has been caused by excavation, resulting in an unevenly slumped top.
Still, it commands extensive views across the Brecon Beacons, with a Black Mountains backdrop that would be the envy of just about any barrow. Just to the northwest across the road, in an area that has seen quarrying, are a couple more low "upright" stones, no more than a foot high, which may also be natural.
In Hay on Wye head west on the B4350, look out for a turning on the left signposted: Capel Y Ffin. Take this turning. Follow this road along. After about 4 km when the road forks, take the right fork. The barrow is a couple of hundred yards on your left - right next to the road.
Taking the forest road out of Hay-on-Wye signposted to Capel-y-Ffin, the single-track road rises steeply on a southerly course. At the top, where the scenery opens out over mountainous moorland, lies the large Twyn-y-Beddau round barrow, as if standing sentry before the even higher land.
Twyn-y-beddau means 'mound of graves'. It is said to be the site of a terrible battle between the Welsh and Edward 1st's supporters. So grim was the bloodshed that the nearby stream was said to have run red for for three days.
(from the trusty Reader's Digest 'Folklore, Myths and Legends of Britain'!)