Edward I invaded North Wales in 1282 with a vast army, ending the independence of the Welsh princes and imposing English rule through a network of fortified towns and castles. The Statute of Rhuddlan in 1284 reorganized Wales into English-style shires, and new castle-towns rose at Caernarfon, Harlech, and Conwy. Plans for a castle on Anglesey were probably drawn up the same year, but the site near the town of Llanfaes was not developed immediately. It took the Welsh revolt of 1294-95, led by Madog ap Llywelyn, to force Edward's hand. The revolt was bloody -- Roger de Pulesdon, sheriff of Anglesey, was among the dead -- and Edward responded by relocating the Welsh population of Llanfaes twelve miles southwest to the newly created settlement of Newborough, clearing the ground for his castle.

Construction began in the summer of 1295 under Master James of St George, the Savoyard architect who designed most of Edward's Welsh castles and who was the foremost military architect of his age. James understood the difficulties. Writing to his employers in the spring of 1296, he detailed the costs and challenges with a directness unusual for the period. The construction was recorded in remarkable detail on the pipe rolls, the continuous ledgers of royal expenditure, making Beaumaris one of the best-documented medieval building projects in existence. Despite the enormous effort of that first summer, momentum soon faltered. Edward's attention and treasury turned to Scotland, and work dropped off sharply after 1296, halting entirely by 1300.

Historian Arnold Taylor called Beaumaris Britain's "most perfect example of symmetrical concentric planning," and UNESCO praised it as a "unique artistic achievement" for the beauty of its proportions and masonry. The design is a castle within a castle: an inner ward of massive walls -- thirty-six feet high and fifteen and a half feet thick -- surrounded by an octagonal outer curtain wall with twelve turrets. A water-filled moat encircled the whole. The Gate next the Sea connected to a tidal dock, allowing supply ships to reach the castle directly. Around 300 firing positions for archers lined the defenses, including 164 arrow slits. Yet the inner walls and towers were never built to their intended height, and the north and northwest sides lacked outer defenses altogether.

Beaumaris saw genuine conflict. Welsh forces under Owain Glyndwr besieged and captured it in 1403, holding it until 1405. During the English Civil War, the castle controlled a route between the king's Irish bases and his English operations, remaining in Royalist hands until Colonel Richard Bulkeley surrendered it to Parliament in June 1646. The castle escaped slighting -- the deliberate demolition that destroyed many English and Welsh fortifications after the war -- and fell gradually into picturesque ruin. Thomas Bulkeley, 7th Viscount Bulkeley, bought it from the Crown in 1807 for 735 pounds and folded it into the parkland surrounding his home at Baron Hill.

In 1832, the future Queen Victoria visited for an Eisteddfod festival. J. M. W. Turner painted the castle in 1835. In 1950, it was designated a Grade I listed building, and in 1986 UNESCO inscribed it as part of the Castles and Town Walls of King Edward in Gwynedd World Heritage Site, recognizing the Edwardian castles of North Wales as among "the finest examples of late 13th century and early 14th century military architecture in Europe." Today Cadw manages the site, which draws about 75,000 visitors a year. The moat is partially filled, the towers truncated, the gatehouses half-built. What remains is a meditation on ambition outstripping resources -- a castle whose imperfection is, paradoxically, what makes it unforgettable.