Sarn Helen
Segontium to Maridunum
The route
Sarn Helen is not one road but the Welsh name given to the chain of Roman roads running the length of Wales from north to south. The northern end is given variously as Segontium, the fort at Caernarfon, or Canovium at Caerhun in the Conwy valley. From there the line runs south-east past the fort at Tomen y Mur near Trawsfynydd, over the moors above Ffestiniog and down through mid Wales.
It continues past the gold mines at Dolaucothi, which the Roman state worked on a large scale, and reaches Maridunum at Carmarthen in the south-west. Several branches and alternative alignments carry the same name locally.
The surveyed line
The Itiner-e survey maps Roman roads across this part of the empire, but attributes no segment to Sarn Helen by name, so there is no measured line to draw here. The road is well attested by archaeology and by the modern roads that still follow it.
The road today
Very little. The A470 shadows the general corridor through mid Wales without following the Roman line closely. A handful of mountain lanes sit directly on it, and several are still signposted Sarn Helen.
See also: which modern roads follow Roman lines, and how closely.
Where to see it
The moorland above Ffestiniog, between Tomen y Mur and Dolwyddelan, has the clearest surviving stretches, where the agger is plain as a raised band in the turf across empty ground.
Dolaucothi Gold Mines, now in the care of the National Trust, is the outstanding destination on the southern half: the only known Roman gold mine in Britain, with surviving aqueduct channels and adits.
Common questions
Who was Sarn Helen named after?
Tradition names Elen Luyddog, Helen of the Hosts, the British wife of the usurper Magnus Maximus in the late fourth century, who was said to have ordered roads built to move her husband's armies. The story is medieval rather than Roman. Some scholars instead derive the name from the Welsh halen, meaning salt, or from y lleng, the legion.
Can you walk Sarn Helen?
Parts of it. There is no single continuous right of way along the whole chain, but long stretches across the uplands of Snowdonia and mid Wales are open access or public footpath and are well worth walking.