Hen Gastell, a small promontory fort (?) on the north bank of the Afon Carog. The very small enclosed area marks this site as a single homestead or farmstead. Not withstanding the strength of the main defence it is certainly not a fort.
(Source OS495 card)
M. Edwards 17 Oct 2001

'Excavations by the Gwynedd Archaeological Trust have now revealed this was a medieval site dating from the 11-12th century, consisting of an embanked platform of oval shape, at the end of a low ridge bordering a stream. The platform held the post-holes of a substantial timber structure, although the full extent was not recovered. It may have been circular, or perhaps more likely a rectangular building with one or more apsidal end. There was a broad ditch with a massive rampart set, unusually, on the outer side of the ditch.'
From notes written by Paul Davis to accompany photographs taken in December 2019
RCAHMW, 14th February 2020