Site description from Coflein:
“A roughly oval hilltop enclosure, 120m by 80m. It is defined by scarp lines except on the north, where there is a bank and ditch and possible entrance approach. Below and to the south, the enclosure is abutted by a possibly contemporary annex, 60m by 40m, banked and ditched on the south. The relation of the enclosure and annex is obscured by the remains of linear quarrying.”
coflein.gov.uk/en/site/92029/details/Y+GAER%3BTWYN-Y-GAER%2C+ENCLOSURE%2C+DEFYNNOG/
A public footpath and bridleway run along the eastern side of the site.