Brithdir Signal Station
A small square earthwork set upon a ridge summit has been identified as a possible Roman military tower. It is set on the crest of a south-facing ridge, commanding extensive views across the upland basin below Pen-y-Brynnfforchog and the course of the Roman road between Caer Gai and Brithdir.
A range of alternative interpretations can be advanced, notably that this is a Roman or early Medieval square ditched barrow, such as are found at Druid beyond Bala, and Croes Faen near Tywyn. As such it would, with Tomen-y-Mur, be a rare surviving earthwork example, most sites being known only from cropmarks. This monument might be compared to the small practice work at Llyn Hiraethllyn, otherwise the smallest example of its type known in Wales.