In 1649 during the English Civil War, Oliver Cromwell had the castle slighted to make sure that it could never be used again. The seat of the de Barry family, this fortified manor house was built in the 13th century to replace an earlier earthwork.Added to and strengthened in the early 14th century, the ruins of which can be seen today. Guarding the approach to the Menai Strait, Beaumaris, or fair marsh, was started in 1295 under the supervision of the king’s favourite architect, Master James of St George.Briefly besieged in 1294, it was attacked again during the early 15th century by Owain Glyndwr, who eventually captured it in 1406.
Although Edward began to rebuild it, a fire gutted the castle and it was left to ruin. Although the Romans had fortified the site centuries before, today’s remains are mainly those of a Norman motte and bailey castle dating from around 1085.Using his favourite architect, Master James of St George, Edward went on to rebuild in stone a great tower on top of the earlier motte, surrounded by a substantial curtain wall with several small towers.In 1282 Llewelyn ap Gruffydd fell into an ambush after leaving the castle and was killed at nearby Cilmeri.The last and largest of the castles to be built by King Edward I in his Conquest of Wales, it was at the time one of the most sophisticated examples of medieval military architecture in Britain.Work on the castle was suspended during Edward’s Scottish campaigns in the early 1300’s, and as a consequence it was never fully completed.