Its artificial defences are now very insignificant, but the site by nature is almost impregnable. The principal entrance, to which a steep, zigzag pathway still conducts, is in the northern angle, facing the bay.
..Tradition connects the spot with the fatal expedition of Gryffydd ab Cynan, prince of North Wales, against the usurper Trahaearn, when he received that signal overthrow at Bron yr Erw, about three quarters of a mile distant. His line of march from Abermenai hither, is still traceable by several traditional designations; such for instance as Bryn Cynan, by Llandwrog, Carreg Cynan above Penarth, and Craig Cynan. From its elevated and conspicuous site, commanding at one glance the fearful pass of Bwlch-dau-fynydd, leading to Lleyn and Eifionydd, the pass of Bwlch Derwydd to Ffestiniog and Ardudwy, together with a multitude of military posts scattered between Segontium and the Rivals, its chief use probably was that of signal and observation.