White Castle, situated near Llantilio Crossenny in Monmouthshire, Wales, is the best-preserved of the trio of Norman 'Three Castles' fortifications built to control the Welsh border. Established by the Normans shortly after the 1066 Conquest, the castle was rebuilt in stone during the 12th century with a square keep surrounded by a curtain wall. The moniker 'White Castle' emerged in the 13th century, referring to the colour of its whitewashed stone walls. The fortress features a distinctive pear-shaped inner ward protected by a deep, steep-sided water-filled moat, with an outer ward as expansive as a football pitch. Today it stands free to visit, showcasing centuries of defensive architecture against Welsh-English border conflicts.