Sarn Helen

Roman Road

Sarn Helen refers to several stretches of Roman road in Wales. The 160-mile (260 km) route, which follows a meandering course through central Wales, connects Aberconwy in the north with Carmarthen in the west. Despite its length, academic debate continues as to the precise course of the Roman road. Many sections are now used by the modern road network while other parts are still traceable. However, there are sizeable stretches that have been lost and are unidentifiable.

The route is named after Saint Elen of Caernarfon, a Celtic saint, whose story is told in The Dream of Macsen Wledig, part of the Mabinogion. She is said to have ordered the construction of roads in Wales during the late 4th century.


In the north the route is believed to follow the western bank of the river Conwy from Caerhun (Canovium), passing through Trefriw, then leading on to Betws-y-Coed, with a branch leading to the Roman Fort at Bryn Y Gefeiliau (Caer Llugwy). The route then passed through Dolwyddelan, running through the Cwm Penamnen valley and past the higher parts of Cwm Penmachno. The route then leads on past Llan Ffestiniog to the Roman fort of Tomen Y Mur Roman Fort, near Trawsfynydd before continuing south towards Dolgellau.

South of Dolgellau the route passes over Waen Llefenni into Cwm yr Hengae to Aberllefenni. Part of the narrow-gauge Corris Railway between Aberllefenni and Maespoeth Junction may run along the line of the Sarn. A minor road running along the east bank of the Afon Dulas near Esgairgeiliog, Powys might be Roman in origin. Although potentially the Roman road remained on the west bank of the Dulas between Corris and Ffridd Gate.

Sarn Helen might have crossed the Afon Dyfi at a ford or ferry near Cefn Caer, a small Roman fort at Pennal in southern Gwynedd.

In Ceredigion part of a B-road at Bronant is Roman, and six miles south is a long stretch through the hamlet of Stag’s Head. The road is identifiable at Llanio, where there was a small Roman fort named Bremia (Llanio). The route then heads southeast towards the Dolaucothi Gold Mines near Pumsaint, Carmarthenshire, before finally reaching its historical end at Llandovery (Alabum) Roman Fort. The Roman encampment was on Llanfair Hill. In the 12th century, the Normans reused part of the site and its earthworks to build the mediaeval church of St Mary’s Church, Llanfair-ar-y-bryn. The fort stood at the junction of Roman roads, linking the Dolaucothi Roman Mines to Carmarthen (Moridunum) and Brecon (Cicucium or Y Gaer).


A further section of Roman road leading north-eastwards from Neath (Nidum) Roman Fort to Banwen at the southern edge of the Brecon Beacons National Park is also known as Sarn Helen. It continues north-eastwards through the park to the north-west of Ystradfellte, beneath Fan Frynych, and then across Mynydd Illtud en route to the Roman fort of Brecon (Cicucium or Y Gaer).

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