The Causeway of Belinus

Tower Point – western end of the Causeway of Belinus

What links the western edge of Pembrokeshire to Oxford and thence to a dragon myth tied to the very foundation of Wales? The answer is an ancient Celtic path known as the Causeway of Belinus.

Almost everything about this dead-straight east-west line is surrounded by foggy folklore mixed with misty history. But one thing is certain: the science and insights of the Druids play a major role in the unfolding of the tale.

The ancient British king Llud, plagued by a pair of squabbling dragons, consulted his brother Llevelys, king of France. Llevelys advised him to calculate the exact centre of Britain and dig a pit there in which to trap the dragons. Once the dragons were captured, they were taken to Dinas Emrys (a hill fort in Snowdonia) and imprisoned there. In one medieval account it is Merlin who sees the dragons as symbols of Wales and its enemies. The red dragon of Wales somehow (and perhaps) emerges from this as a national icon.

Llud calculated that the exact centre of Britain was Oxford – and the line from Oxford to Dina Emrys turns out to be a clear and accurate solstice line.

But now comes the most intriguing spin-off. According to the 12th-century historian Geoffrey of Monmouth, a mythical British king called Belinus ordered that a causeway should be drawn across the country from the Demetian Sea (part of the Irish Sea, named after the Demetae tribe of south-west Wales) to the medieval port of Maeldun (Maldon, Essex).

The most detailed account of all this is contained in a brilliant investigation of Druidic geometry and geography, The Ancient Paths by Graham Robb (published by Picador).

Robb explains that the Causeway line went straight through Oxford (of course) and also through the original sites of the historic towns of Chelmsford and St Albans and a series of significant Iron Age and Dark Ages forts, including Pen-y-Darren (Merthyr Tydfil), Cymbeline’s Castle (Buckinghamshire), and Alt-Cunedda and Coygan Camp, both in Carmarthenshire.

And the far western end of the Causeway coincides exactly with Tower Point, near St Brides and Marloes in Pembrokeshire.

Anyone who has explored around Tower Point will be well aware that the landscape of the promontory here vividly displays the site of a large Iron Age fort. At the rear the fort was protected by steep cliffs, and at the front it was defended by a bank and a ditch.

To follow the line due east from Tower Point is to take a journey through Welsh and British history. 

Near the site of the Coygan Camp fort and also on the Causeway is the ancient church of St Margaret Marloes, just over the Pembrokeshire border in Eglwyscummin, Carmarthenshire. There was a church here as long ago as the 5th century, and many churches were founded in places held sacred by earlier religions. It is truly an atmospheric building in a magical setting, and well worth a visit. I have tried somewhat desperately to find a link between St Margaret Marloes and Marloes in Pembrokeshire – and so far failed. Like much in the history of such far-off times, it may well be a complete coincidence.

The Causeway of Belinus may or may not have been a literal road; it was more likely to have been an ancient form of satnav, guiding travellers from one place to another, just as were the many solstice lines identified by the Druids across Gaul/France (and by Graham Robb’s book). Whatever the truth, there is defiinitely much food for historical thought along the Causeway’s remarkable route.

Nigel Summerley

Nigel Summerley retired from The Oldie magazine to return to freelance journalism. He previously held executive staff jobs at the London Evening Standard, The Daily Telegraph, The Sunday Telegraph and the Daily Express before freelancing for 20 years for newspapers including The Times, The Sunday Times, The Independent, The Guardian and the ‘i’ paper, plus a wide range of magazines. He continues to write about music, travel and health, and blogs at

You may also like...

1 Response

  1. March 23, 2020

    […] of Merlin ties in with Pembrokeshire.Online’s earlier story about the Causeway of Berlinus ( As recounted there, Britain was long ago plagued by two warring dragons which were eventually […]