Conwy Castle was created during Edward I’s invasion and occupation of north Wales. Work began in 1283, immediately after the king’s forces took control of the lower Conwy valley, and continued at exceptional speed until 1289. James of Saint George, Edward’s leading master mason, directed an international workforce of masons, carpenters, quarrymen, and laborers. The fortress and the adjoining walled town were planned together, replacing the nearby center of the Welsh princes at Deganwy with a new English royal borough and military base.

The castle’s position on a rocky ridge above the River Conwy gave it access to supplies by water and command of a strategic crossing. Eight great towers and two fortified gateways enclosed a narrow inner and outer ward. The inner ward contained the king’s apartments, queen’s chambers, hall, chapel, and service rooms; the outer ward held the great hall, kitchens, and garrison accommodation. This division allowed the royal household to live with considerable ceremony while the walls, arrow loops, battlements, and sea gate supported defense.

Conwy’s most severe test came during the Welsh rising led by Madog ap Llywelyn in 1294–95. Edward I was briefly isolated in the castle over Christmas while rebels controlled surrounding territory, but ships could provision the garrison from the river. The episode demonstrated why the crown had linked its castles to navigable water. In 1401 supporters of Owain Glyndŵr captured Conwy through deception and held it for several months. Negotiations ended the occupation, and the stronghold returned to royal control without a major assault.

Maintenance declined after the later Middle Ages, although Conwy remained a royal property and occasional administrative center. During the English Civil War, Archbishop John Williams repaired and garrisoned it for Charles I. Royalist forces held the castle until 1646, when Parliamentarian troops took it after a siege. Its lead and useful fittings were subsequently stripped, accelerating decay. By the eighteenth and nineteenth centuries the roofless towers and halls had become celebrated picturesque ruins, attracting artists, antiquarians, and travelers moving through north Wales.

Conwy retains the complete circuit of its curtain walls and all eight towers, while the vanished roofs and floors leave the domestic ranges open to view. Conservation has favored the legibility of medieval masonry rather than rebuilding the royal rooms. Cadw cares for the monument, which forms part of the UNESCO World Heritage Site encompassing Edward I’s castles and town walls in Gwynedd. Together with Conwy’s surviving urban walls, the castle records how conquest was imposed through architecture, settlement, supply networks, and a permanent royal presence.