Rhuddlan Castle Rhuddlan Castle ( ) is a castle located in Rhuddlan , Denbighshire , Wales . It was erected by Edward I in 1277 following the First Welsh War . Construction . Rhuddlan was planned as a concentric castle . It has a unique ' diamond ' in layout as the gatehouses are positioned at the corners of the square baileys instead of along the sides like at Flint , Harlech or Beaumaris . The inner ward has defensive wall s with twin - tower gatehouses . The outer ward is surrounded by a curtain wall that has small towers and turrets . The castle also had a dry moat to improve defence on its landward side . Within the inner ward there was a great hall , kitchens , private apartments and a chapel . The outer bailey had a granary , stables and a smithy . Much of the work was overseen by master mason James of St George . Rhuddlan , which was not completed until 1282 , was built concurrently with Flint Castle . Rhuddlan is next to the River Clwyd . During the fortification ' s lengthy construction , the river course was straightened and dredged to allow ships to sail inland along a man - made channel . Its purpose was to allow provisions and troops to reach the castle even if hostile forces or a siege prevented overland travel . History . The story of Rhuddlan goes back much further than the fortress built by Edward I . Prior to the Norman occupation of lower Gwynedd , Rhuddlan was at the heart of a Welsh cantref . From here the Lords of Rhuddlan commanded the lands of North East Wales ( Welsh " Perfeddwlad " ) on behalf of Gruffydd ap Llywelyn ( 1007 – August 5 , 1063 ) , the last ruler of all Wales . But in the late 11th century , the Normans invaded Gwynedd . Rhuddlan was fought over by the Princes of Gwynedd and the Earls of Chester . The remains of a Norman castle at Twthill , built in 1086 , is just to the south of the current castle . In July 1277 , at the outbreak of the Welsh Wars , Edward I left Chester and established an advance base at Flint , where building work immediately began on Flint Castle . With naval assistance from 25 ships of the Cinque Port s fleet , the army pushed along the coast . By August Edward had moved his forces onto Rhuddlan . Three months later it was ceded to the English Crown following the Treaty of Aberconwy between Llywelyn II of Gwynedd and Edward I . Work on Rhuddlan Castle began immediately under the control of Master Bertram , a Gascon engineer , but construction was soon handed over to Savoyard master mason , James of St George who remained in charge until labour ceased in 1282 . Edward I also created a new borough , north of his castle , away from the pre - existing Norman town and Dominican Friary . The 13th - century street layout can still be seen in the modern town . The borough , like at Flint , was defended with a pair of ditch - separated earthworks and a timber palisade . Elizabeth the eighth daughter of Edward I was born at Rhuddlan in 1282 , the same year work at the castle was completed . Two years later the Statute of Rhuddlan was signed at the castle following the defeat of Llewellyn the Last . It ceded all the lands of the former Welsh Princes to the English Crown and introduced English common law . Edward I could now appoint Royal officials such as sheriff s , constable s , and bailiff s to collect taxes and enforce English law throughout Wales . Following Rhuddlan , the counties of north western North Wales were placed under the control of the Justiciar of North Wales . Although the statute brought in English legislation , Welsh law continued to be practised at local level after the conquest of the Wales . This remained the case until 1536 when Rhuddlan ' s statute was repealed by the Laws in Wales Acts 1535 - 1542 that made English common law the exclusive judicial system in Wales . In 1294 the castle was attacked during the Welsh rising of Madog ap Llywelyn but was not taken . It was attacked again by forces of Owain Glyndŵr in 1400 . This time the town was badly damaged but the castle held out . In the latter 15th and early 16th centuries the castle ' s condition deteriorated as its strategic and administrative importance waned . Rhuddlan Castle was again garrisoned by Royalist troops during the English Civil War . It was taken by Parliamentary forces after a siege in 1646 . Two years later Parliamentarians partially demolished the castle to prevent any further military use . Present day . Today Rhuddlan Castle is managed by Cadw , a Welsh - government body with the mission to protect , conserve and promote the building heritage of Wales .