Castell Arnallt

Castell Arnallt stands in Monmouthshire, near the village of Llanover in the Usk valley. It was the fortified court house of Seisyll ap Dyfnwal, lord of Over Gwent, before its destruction in the 12th century. The site lies about four miles south-east of Abergavenny and is now used for grazing. No visible remains survive above ground, only a large oblong mound in pasture land. Two enclosures mark the top and western side of the mound. Evidence suggests buried structures, a gate, and masonry walls beneath the surface. The castle was linked to Dyfnwal ap Caradog’s estates and may have been built before 1175. Seisyll ap Dyfnwal was recognised by King Henry II as lord of Over Gwent. In 1175, William de Braose attacked Abergavenny Castle, leading to the deaths of Seisyll and his household. Castell Arnallt was razed in a surprise raid, and Seisyll’s son Cadwaladr was killed during the attack. The site has been surveyed but not excavated. It was scheduled as an Ancient Monument in 1947. In 1325, the land passed to Sir William de Hastings. Today, the mound sits on the edge of the River Usk’s flood plain, offering a quiet spot in agricultural land. The absence of visible ruins adds to the site’s quiet, reflective atmosphere.