The Oernant Quarry Tramway linked the slate quarries on Moel-y-Faen (SJ187 476) and Bwlch yr Oernant with the wharfs on the Llangollen (Ellsemere) Canal at Pentrefelin. The canal was the only one in Wales that was used to move slate in such industrial quantities, and the slate would be taken to towns, cities and ports, from which it would sold throughout the world.
The slates that were loaded up onto barges at Pentrefelin roofed homes throughout the world.
There is some evidence that quarrying at Moel-y-Faen began in the 17th century with the production of slate slabs and possibly roof slates, but developed significantly with the opening of the Ellesmere Canal. The tramway was opened in 1852 and came down the fringes of the Llantysilio Mountains, along the incline at Maesyrychain (SJ 197 448) before reaching the wharfs at Pentrefelin, north west of Llangollen and close to the Llantysilio road.
The River Eglwyseg runs beneath the tramway before joining the Dee.
The viaduct, which though largely overgrown, is still visible from the road, crossing the Eglwyseg River. It was thought to have been built with stone recovered from Valle Crucis Abbey.