A circular walk around the most interesting sites of the Preseli Hills is almost impossible. The uplands form an isolated east-west ridge that would at best form one side of a circuit linked with a lengthy road section. Instead of taking this less-than-ideal option, this walk forms a contorted and narrow figure-of-eight that scales the most spectacular hill on the ridge, traces the line of the famous dolerite outcrops, or carns, and then makes an out-and-back sortie to an impressive stone circle. Convoluted it may be, but it's packed with interest and easy going enough for most people to complete comfortably.

Preseli Hills

The Pembrokeshire Coast National Park is best known for its stunning coastline. Britain's smallest National Park is in no single place further than 10 miles (16.1km) from the sea. This furthest point was a deliberate extension of the boundaries to incorporate one of the most important historic sites in the United Kingdom, the Preseli Hills.

Carn Menyn's bluestones

It was from Carn Menyn, one of the rocky tors that crown the marshy and often windswept hills, that the bluestones forming the inner circle of Stonehenge were taken. These bluestones, or spotted dolerite stones to give them their proper name, would have each weighed somewhere in the region of 4 tonnes and must have been transported over 200 miles (320km) in total. To this day we cannot explain how or why.

Ancient road

The Stonehenge story, significant as it may be, is only part of the historic and, at times, mystical feel of this narrow, grassy upland. The track that follows the ridge is an ancient road, perhaps dating back over 5,000 years. It's probable that it was a safe passage between the coast and the settlements inland at a time when wild predators such as bears and wolves roamed the valleys below. Gravestones line the track, most likely those of travellers or traders who were buried where they died, and other standing stones dot the hillsides.

Beddarthur

West of Carn Menyn, beneath another impressive outcrop named Carn Bica, there's a stone circle known as Beddarthur. Small by comparison to Stonehenge or Avebury, its oval arrangement of 2ft–3ft (0.6m–1m) high stones is said to be yet another burial place of King Arthur; 'bedd' means grave in Welsh. There are certainly links between the legendary historical superhero and the area; it's suggested that the King and his knights chased Twrch Trywyth, the magical giant boar, across these hills before heading east

From the lay-by on the lane from Crymych, walk straight up a stony track opposite, then turn right up a stony track. When you reach three gates, keep going straight ahead for another 100yds (91m) or so, and then fork left on to a grassy track, which soon becomes clearer as it winds its way up the hillside. Follow this all the way to the rocky cairns and trig point on Foel Drygarn.

Bear left at the summit and locate a grassy track that drops steeply to the south. Cross the heather-clad plateau beneath, aiming for the left-hand corner of a wood. When you meet the main track, turn right to walk with the edge of the wood on your left.

Leaving the wood, the path climbs slightly to some rocky tors. As you pass the tor to the left of the track, the path forks and you follow the left-hand track to the nearest of the group of outcrops to your left.

This is Carn Gyfrwy. Continue on faint paths to the larger outcrops ahead, then curve right away from the stones and drop slightly to Carn Menyn, the lowest of the bunch, perched precariously on the edge of the escarpment. The path becomes clearer here and drops slightly into a marshy saddle that can be seen ahead.

In the saddle you'll meet the main track. Turn left and follow it steadily up towards Carn Bica, which is visible on the hillside ahead of you. Just before this, you'll cross the circle made by the stones of Beddarthur.

Turn around and retrace your steps back to the saddle. Climb slightly to pass the tor where you turned left to Carn Gyfrwy on your way out, ignoring the paths forking right to Carn Menyn, and stay on this main path to walk beside the plantation once more, now on your right. At the end of this, continue straight on, following a fence-topped wall to your right, down to the gate. Turn right on to the lane and continue back to the car park.