Abergwyngregyn  Abergwyngregyn () is a village and community of historical note in Gwynedd, a county and principal area in Wales. Under its historic name of Aber Garth Celyn it was the seat of Llywelyn ap Gruffudd. It lies in the historic county of Caernarfonshire. It is located at , adjacent to the A55, five miles (8 km) east of Bangor, eight miles (13 km) west of Conwy. The Aber community, which covers an area of , has a population of 240 (2011). Abergwyngregyn, generally shortened to Aber, is a settlement of great antiquity and pre-conquest importance on the north coast of Gwynedd. Its boundaries stretch from the Menai Strait up to the headwaters of the Afon Goch and Afon Anafon. Protected to the east by the headland of Penmaenmawr, and at its rear by Snowdonia, it controlled the ancient crossing point of the Lafan Sands to Anglesey. A pre-Roman defensive enclosure, Maes y Gaer, which rises above Pen y Bryn on the eastern side of the valley, has far reaching views over Irish Sea with the Isle of Man visible on a clear day. The Roman road from Chester (Deva), linking the forts of Canovium (later name Conovium) and Segontium, crossed the river at this point. This was the seat of Llywelyn ap Gruffudd, the last native Prince of Wales, whose daughter Gwenllian of Wales was born here in June 1282. His wife, Eleanor de Montfort, died here as a result of the birth on 19 June 1282. In June 1283 Dafydd ap Gruffudd, Llywelyn's brother, who assumed the title of Prince of Wales after Llywelyn's murder in December 1282, was captured at Bera Mountain above the present village. Abergwyngregyn was one of ten sites chosen for the Welsh Cultural Heritage Initiative in 2009. Y Mŵd is an earthen mound on the valley floor in the middle of the village, at . The mound is circular, high with a level oval top by . It has been regarded as the base of a Norman castle, and on that basis was renamed 'Aber Castle Mound' by the Ancient Monuments Board. Armitage, in The Early Norman Castles of the British Isles, suggested that it might have been constructed by Hugh d'Avranches, Earl of Chester.