White Castle , Wales White Castle ( ) , Llantilio Crossenny is a medieval castle in Monmouthshire , Wales . The name " White Castle " was first recorded in the thirteenth century , and was derived from the whitewash put on the stone walls . The castle was originally called Llantilio Castle ( recorded in the Pipe Rolls in 1186 ) , after Llantilio Crossenny , the medieval manor of which it was a part . Known as one of the “ Three Castles ” , there has been a defensive structure at the site since the late eleventh century . The castle ruins are Grade I listed as at 19 November 1953 . History of “ The Three Castles ” . The term “ The Three Castles ” is used to collectively describe White Castle , Skenfrith Castle and Grosmont Castle , all of which are located in the Monnow Valley in south Wales in modern - day Monmouthshire . The River Monnow valley was an important route between Hereford and South Wales in medieval times , due to its position as an area of relatively open land , which provided a break between the river cliffs of the Wye Valley to the east , and the hills around Abergavenny to the west . The Three Castles are usually grouped together by historians because for almost their entire history they were part of a block of territory under the control of a single lord . All three sites have evidence for early Norman earthworks , possibly built by William fitz Osbern , who was made Earl of Hereford by William the Conqueror a few months after the Norman Conquest of England in 1066 . From his castles at Monmouth and Chepstow , William was the first Norman lord to conquer central and eastern Monmouthshire , including the future sites for the Three Castles . The defenses raised at this time would have been of earth and timber , probably in the classic Norman motte - and - bailey style . Fitz Osbern died in 1071 , and his lands were forfeited to the Crown after his son Roger de Breteuil was involved in a rebellion against King William in 1075 . In order to prevent the rise of such a powerful magnate , the King divided up this strategically important territory – the only time in their active history that the Three Castles were owned separately . They were reunited by King Stephen before July 1137 and would remain a single lordship until the nineteenth century . There is little evidence of building activity at any of the castles until the late twelfth century , when they were fortified by Ralph of Grosmont , a Royal official who supervised building work for the King in Hereford . Ralph was responsible for building the towering curtain wall around the inner ward in 1185 – 87 . The castles were later completely overhauled by Hubert de Burgh , who was granted lordship of the Three Castles by King John in 1201 . Control of the Three Castles was briefly granted to William de Braose in 1205 , when Hubert was a prisoner of Philip Augustus , the King of France , but William de Braose quickly fell out of favour , and by 1207 King John had forced him into ruin . Hubert de Burgh returned to power , and was appointed Justiciar in 1215 . From his time fighting in France Hubert had a knowledge of the latest in military architecture , and in the years after 1219 he was a prosperous lord who had great influence with the young King Henry III . He rebuilt Skenfrith between 1219 and 1222 and Grosmont between 1224 and 1226 in stone , adding domestic apartments to both castles , so that they could be used as lordly residences . He held the Three Castles until 1239 , although they were briefly taken from him after he fell out of Royal favour in 1232 ( they were returned after his reconciliation to the King two years later ) . Hubert first added four round towers to the inner ward of White Castle in the period 1229 to 1232 . One pair of these made the great gatehouse . After his return to royal favour in 1234 he added to the two great D - shaped towers to the inner ward and built the masonry outer ward . He was probably also responsible for demolishing the original square Norman tower keep . On the king resuming the castles in 1239 Hubert was said by Matthew Paris to have spent a small fortune on their building . After Hubert de Burgh , the Three Castles were held in Royal hands , and in 1254 Henry III granted them to his eldest son , the future Edward I . In the 1260s the southern March was threatened by the Welsh prince Llewelyn ap Gruffudd , who annexed the lordship of Brecon , and attacked nearby Abergavenny . Gilbert Talbot was appointed Constable of the Three Castles , and ordered to garrison them ‘ at whatever cost ’ . Although Llewelyn ’ s attack on Abergavenny failed , the Treaty of Montgomery in 1267 recognized his southern conquests , and he was considered a significant threat . 1267 saw the Three Castles being granted to Edward ’ s younger brother Edmund , Earl of Lancaster . Although the Welsh threat was soon subdued with the death of Llywelyn in 1282 , the Three Castles were used as residences and centres for local authority . The castles passed down through the Earls of Lancaster until the death of Henry of Grosmont , Duke of Lancaster , whose daughter Blanche married John of Gaunt , son of Edward III . John of Gaunt was made Duke of Lancaster in 1364 , and the Three Castles would remain part of the Duchy of Lancaster until 1825 . John and Blanche ’ s son , Henry of Bolingbroke , deposed Richard II in 1399 and became King as Henry IV , at which time the Three Castles also became Royal possessions once more . Although the Three Castles briefly saw action during the rebellion of Owain Glyndŵr in 1404 – 05 , they never again played a major role in military affairs . Henry VI carried out repairs to White Castle and Skenfrith Castle in the mid fifteenth century , but by 1538 the castles were abandoned , and ruinous . In 1825 the Duchy of Lancaster sold the castles to the duke of Beaufort , whose estate divided them and sold each to different local landowners in 1902 . White Castle was given to the State in 1922 , followed by Grosmont in 1923 . Skenfrith passed through several hands before being given to the National Trust . All three castles are now conserved and maintained by Cadw , and are open to the public . Building of White Castle . The earliest castle at this site consisted of two earthworks – the pear shaped inner ward with a surrounding water - filled moat , and a crescent shaped outer bailey to the south known as the hornwork . To the north of the inner ward was a large area enclosed by a defensive bank , which may have been used for armies in the field to camp in safety , without fear of a surprise attack . The earliest buildings and walls were almost certainly built of wood , although a square stone keep was added sometime before the stewardship of Ralph of Grosmont , who recorded an expenditure on “ the dwelling in the tower of Llantilio ” in the Pipe Rolls of 1186 – 87 , implying that structure was already present . Further monies spent at the site were most likely for the construction of a stone curtain wall around the inner ward . Like its fellow Monnow Valley strongholds , White Castle was significantly altered by Hubert de Burgh as has been described above . The orientation of the castle shifted , with entry no longer through the southern hornwork . Instead , a new twin - towered gatehouse was built at the northern end of the inner ward . Wooden drawbridge s would have controlled access from both the north and the south of the castle . Within the inner ward there would have been residences , great hall , a chapel , kitchen and brewhouse . Hubert ' s work here can be compared to Montgomery Castle which he also held and helped design between 1223 and 1232 . The hornwork , now at the rear of the castle , was maintained as a defence for a small rear postern gate . The northern enclosure , previously defended by an earthwork , was built into a large outer bailey , with four projecting towers and a gatehouse on its eastern corner . Geophysical evidence suggests that there were small timber buildings within the walls of the outer ward , as well one large building , thought to be used as a barn . Visiting the castle . White Castle was frequently visited and , apparently , painted by German Deputy Führer Rudolf Hess during the period when he was held in Maindiff Court Military Hospital at Abergavenny , between 1942 and his trial in 1945 . The castle today stands in partial ruin , although there have been few significant losses to time . The stone walls and towers of the inner and outer ward still stand , although their inner floors are missing , as are portions of the upper level of the walls . A modern wooden bridge spans the moat between the inner and outer ward , and within one tower of the inner gatehouse the stairwell has been restored , allowing access to the top of the tower , and a commanding view of the surrounding countryside . The castle is maintained by Cadw , and access is controlled during the summer months . The rest of the year the castle is an open site , and may be visited at any reasonable time of day . White Castle is located 1 mile north of the village of Llantilio Crossenny , along the B4233 between Monmouth and Abergavenny .