Foeldrygarn, Bedd Arthur, Carn Sian and Mynachlog-ddu

The summit of Foeldrygarn (Three Cairn Hill) beckons you from the beginning of the walk. From here there is a commanding view, including the Black Mountains to the east, and extending to Snowdonia in the north, and the Wicklow Hills across the Irish Sea to the west. The summit from which this magnificent view can be enjoyed has three Bronze Age cairns which give the hill its name. One large flat stone is called Bwrdd y Brenin (The King's Table) and is said to conceal a pot of gold.

The Golden Road was an early Bronze Age trade route. Its name is a reminder that gold was brought along it from the Wicklow Hills. It was still important as a drove road for Welsh Black cattle in the 19th century. It leads past Carn Menyn, from which most of Stonehenge's bluestones originate. Similar stones weighing about four tons each still litter the site, as if cut ready for transportation.

There are many curious blocks and slabs of rock poised precariously on top of each other, suggesting animal or bird figures, while the top of the distinctly shaped Warrior Stone resembles a helmet. These are works of nature; frost shattered the bedrock when the ground was frozen solid during the last Ice Age. When the glaciers retreated, these great, tumbled forms were left on the surface.

It has long been a mystery how so many of these stones found their way to Wiltshire, where they formed the inner circle and the inner horseshoe of Stonehenge. When Geoffrey of Monmouth wrote his History of the Kings of Britain in the 12th century, he stated that Merlin transported the stones of Stonehenge from Ireland. This is not inconsistent with their origin. In this part of Wales, which was considered Irish in Merlin's Day, an Irish king ruled it, and an Irish language was spoken here.

It became fashionable for a while to believe that these stones were erratic blocks, carried to within easy reach of Stonehenge by glaciers. Recently, stones that were apparently lost in transit have been dredged up in the rivers of south Dyfed, suggesting that they were, in fact, moved there by prehistoric men.

At least five stones of volcanic ash from this magical site were also taken in ancient times to Stonehenge. More recently, in Iron Age times, a hill fort enclosed the summit and an outer enclosure, possibly for cattle, was added.

In the Dark Ages, King Arthur reputedly rode this way with his knights to fight the Twrch Trwyth (Stinking Boar). A bit further along the path is Bedd Arthur, an oval formed by fifteen stones. Below it is Carn Arthur, a great bluestone rock balanced on a pile of boulders. Nearby, Carn Sian is said to be the site of St Silyn's Chapel.

The connection with King Arthur is recorded in the story of Cullwch and Olwen in the medieval collection of Welsh tales, the Mabinogion, Arthur chased after the Twrch Trwyth from Ireland and caught up with him and his host here. Standing at bay in Cwm Cerwyn, Twrch Trwyth slew four of Arthur's champions and then four more, including Arthur's son Gwydre.

Tradition suggests a second of Arthur's sons was killed because there are two standing stones in the monument known as Cerrig Meibion Arthur. This is a bleak spot inspiring thoughts of what might have been if Arthur's sons had not died so young. A recognised heir may have prevented the civil war that allowed the Saxons to shape Britain's destiny.

One of the most convincing theories to explain the legend of Arthur and the Twrch Trwyth is that the boars head was the emblem of the Vandals. As reinforcement to this idea, Geoffrey of Monmouth has Arthur sailing to Ireland to deal with African invaders. If it is accepted that King Arthur was an authentic 6th century ruler (the son of Meurig) from Gwent, he could well have fought the Vandals here after they had been expelled from North Africa by the forces of the Byzantine Empire.

There are more mysterious standing stones, cairns and bluestones to see on the remainder of the walk. And at the village of Mynachlog-ddu there is evidence of more recent history, including a memorial to the poet and champion of the Welsh language. Waldo Williams (1904–1971). He was a pupil at the primary school (where his father was headteacher) between 1911 and 1915, where he learned to speak Welsh. The memorial to him is at nearby Rhos Fach.