Castell Bryngwyn

Castell Bryngwyn stands on the Isle of Anglesey, just west of the village of Brynsiencyn. It is a prehistoric enclosure formed by a circular clay and gravel bank, still rising about 1.5 metres high and faced with stone walls. The flat interior measures roughly 54 metres across. The site’s Welsh name means ‘White Hill Castle’, and since 2024 Cadw has used the spelling Bryngwyn. Archaeologists think the first earthworks were raised at the end of the Neolithic period, around 2500–2000 BC. Fragments of Neolithic pottery found here suggest it may have served as a religious sanctuary or henge. During the Iron Age the walls were built, and later rebuilt in Roman times. A nearby footpath leads from the A4080 to the site. Visitors walk along a low ridge that runs southwest to the Bryn Gwyn stones and northeast past the vanished stone circle of Tre’r Dryw Bach. After half a mile the path reaches Caer Lêb and a small roadside parking area. The grassy banks and wide views across Anglesey give a sense of the site’s long history.