The course of the Roman road from Brithdir to Cefn Caer, near Pennal, identified by D. Hopewell and J. Burman (GAT) from LiDAR as surviving as a feint, low agger (causeway earthwork) broadly parallel and to the north-west of the present road.

Source: Gwynedd Archaeological Trust database, reference number 17725
RCAHMW, 10th October 2018.