The Castles and Town Walls of King Edward in Gwynedd is a UNESCO-designated World Heritage Site located in North West Wales (specifically Gwynedd until 1996). It includes the castles of Beaumaris and Harlech, and the castles and town walls of Caernarfon and Conwy. UNESCO considers these sites to be the "finest examples of late 13th century and early 14th century military architecture in Europe."

The fortifications are part of the Ring of Iron, built by Edward I after his invasion of North Wales in 1282. Edward defeated the local Welsh princes in a major campaign and began permanently colonizing the area. He created new fortified towns, protected by castles, where English immigrants could settle and govern the territories. The project was very expensive and used most of the king’s resources. In 1294, new Welsh revolts led by Madog ap Llywelyn occurred. Conwy and Harlech were supplied by sea and held out against the attack, but Caernarfon, which was still only partially built, was captured. After this, Edward renewed the building efforts and started work on Beaumaris. However, Edward’s wars in Scotland began to drain royal funds, and construction slowed again. By 1330, work on all the fortifications had stopped, and Caernarfon and Beaumaris were not fully completed.

These fortifications played an important role in conflicts in North Wales for many years. They were involved in the Welsh Revolt of the early 15th century and the Wars of the Roses in the late 15th century. After the Tudor dynasty took the throne in 1485, their military importance declined, but they were used again during the English Civil War in the 17th century. After the war, Parliament ordered the slighting, or deliberate destruction, of parts of Conwy and Harlech. However, the threat of a pro-Royalist invasion from Scotland kept Caernarfon and Beaumaris intact. By the end of the 17th century, the castles had fallen into ruin. They became popular with visiting artists during the late 18th and early 19th centuries, and more visitors came as access to the region improved during the Victorian era. In the 20th century, the British government invested heavily in restoring the castles and town walls, bringing back many of their medieval features. In 1986, the sites were declared a World Heritage Site for their outstanding examples of 13th-century fortifications and military architecture. Today, they are managed as tourist attractions by the Welsh heritage agency Cadw.

For much of the 20th century, the castles and walls were studied mainly for their military use. Their use of concentric defenses, barbicans, and large gatehouses led historian D. J. Cathcart King to call them the "zenith of English castle-building," and Sidney Toy described them as "some of the most powerful castles of any age or country." In the late 20th and 21st centuries, historians like Michael Prestwich and Abigail Wheatley also noted their roles as palaces and symbols of royal power. Castles such as Caernarfon and Conwy were built on sites once belonging to Welsh princes, chosen for their political and military importance. These castles included luxury apartments and gardens, designed to support large royal courts. Caernarfon’s castle and town walls used expensive stonework, likely meant to remind people of Arthurian or Roman imperial power, to strengthen Edward’s reputation. The exact role of the royal architect James of Saint George in the projects, and how his native County of Savoy influenced the designs, is still debated by scholars. However, historical records clearly state his key role, calling him "Master James of Saint George, Master of the King’s Works in Wales."

History

The Edwardian castles and town walls in Gwynedd were built because of wars fought to control Wales in the late 13th century. The kings of England and Welsh princes had competed for control of the region since the 1070s, with Norman and English nobles and settlers slowly expanding their lands over many years. In the 1260s, the Welsh leader Llywelyn ap Gruffudd used a civil war between Henry III and rebel barons in England to become the dominant power. He was officially recognized as the prince of Wales under the Treaty of Montgomery.

Edward I became king of England in 1272. Edward had experience with warfare and sieges, having fought in Wales in 1257, led the six-month siege of Kenilworth Castle in 1266, and joined a crusade to North Africa in 1270. He had seen many European fortifications, including the planned walled town and castle design at Aigues-Mortes. After becoming king, Edward first renovated and expanded the royal fortress of the Tower of London. He also built a series of planned, walled towns called bastides across Gascony to strengthen his authority in the region and authorized new planned towns to be built in England.

Relations between Edward and Llywelyn quickly worsened, leading Edward to invade North Wales in 1276 to challenge Llywelyn’s power. During the war, Edward built several major castles to control the region and serve as bases for military campaigns. Edward was successful, and the Treaty of Aberconwy in 1277 confirmed English dominance, dividing most of Llywelyn’s lands among his brothers and Edward.

Edward and his allies among the Welsh princes soon quarreled, and in early 1282, a rebellion led by Llywelyn’s brother, Dafydd ap Gruffydd, broke out. Edward responded by gathering a royal army of 8,000 foot soldiers and 750 horsemen, marching them north to Rhuddlan, while Marcher Lord forces advanced from Carmarthen and Montgomery. Edward also launched a naval invasion of the Isle of Anglesey and built a temporary bridge to cross onto the mainland, taking the war into the Welsh heartlands of Snowdonia. Llywelyn was killed in December 1282, and Dafydd was captured and executed in early 1283.

Instead of repeating previous treaties, Edward chose to permanently colonize North Wales. The remaining members of Llywelyn and Dafydd’s royal family were defeated, and their lands were divided among English nobles. Wales was reorganized under the Statute of Rhuddlan, enacted on 3 March 1284. Wales was divided into counties and shires, similar to how England was governed, with three new shires created in the north-west: Caernarfon, Merioneth, and Anglesey.

As part of this plan, Edward ordered the construction of new castles and walled towns across occupied territories to encourage migration from England. These included Caernarfon Castle and its walled town, overlooking the River Seiont; Conwy Castle and its walled town, controlling a crossing point over the River Conwy; and Harlech Castle, protecting a sea port and newly established English town. Plans were made to build a castle and walled settlement near Llanfaes on Anglesey, later called Beaumaris, but were delayed due to the costs of other projects.

The new towns became important centers for England’s new government: Caernarfon and Harlech were the centers of new shires, and Conwy was responsible for a new county. The castles were key military centers but were also designed to function as royal palaces, capable of supporting the king and queen’s households. Some projects had symbolic importance. Conwy was built on the site of Aberconwy Abbey, the traditional burial place of Welsh princes, which was moved inland. The Welsh had valued the Roman site at Caernarfon for its imperial symbolism, and parts of the Welsh princes’ fortifications were reused in Edward’s castle. Harlech Castle’s site was linked to the legend of Branwen, a Welsh princess.

Edward used trusted architects and engineers, including James of St George, Otto de Grandson, Sir John de Bonvillars, and John Francis, to oversee the projects. The new castles were larger and more expensive than those built by local Welsh rulers. Workers, including carpenters, ditch diggers, and stonemasons, were gathered by local sheriffs from across England and sent to North Wales each spring, returning home in winter. The number of workers placed a heavy strain on England’s labor force. Costs were high: Caernarfon Castle and its walls cost £15,500, Conwy Castle and its walls cost around £15,000, and Harlech Castle cost £8,190 to build.

The walled towns were planned in a regular layout, inspired by French bastides and English planned settlements. Their residents were English migrants, while the local Welsh were banned from living inside the walls. The towns had mixed success. Conwy had about 99 burgages (town properties rented from the Crown) by 1295, and Caernarfon had 57 by 1298. Harlech lagged behind, with only 24.5 burgages in 1305. Castles were managed by constables, who defended them and, in some cases, the town walls. Permanent garrisons of soldiers were stationed at Caernarfon (40), Conwy (30), and Harlech (36), equipped with crossbows and armor. The castles and towns could be supplied by sea if needed, a strategic advantage as Edward’s navy controlled the Welsh coastline. Each castle had a rear gate for resupply by sea even if the town had fallen.

Edward’s fortifications were tested in 1294 when Madog ap Llywelyn rebelled against English rule, the first major uprising since the conquest. The Welsh rose up over new taxes, and Madog had strong support. By year’s end, Edward returned to Wales with a large army, reaching Conwy by Christmas. He was trapped and besieged until January 1295, supplied only by sea, and was relieved in February. Harlech was also besieged but saved by supplies from Ireland. Caernarfon, still partially completed, was stormed by Welsh forces, and the castle and town were set on fire. In Anglesey, Welsh forces killed the royal sheriff. In the spring, Edward launched a counterattack with 35,000 soldiers, crushing the rebellion and killing Madog.

After the rebellion,

Architecture

The Castles and Town Walls of King Edward in Gwynedd included many military features built in the late 1200s. For most of the 1900s, historians believed these sites were the highest point of scientific military architecture. D. J. Cathcart King called them the "highest point of English castle-building," and Sidney Toy said they were "some of the most powerful castles of any age or country." The sites had concentric defenses, where inner walls were completely enclosed by outer walls. The walls were built at specific heights and angles so that both sets of walls could fire at attackers, as seen at Harlech and Beaumaris. Narrow areas like Conwy were built on tall rock formations, making attacks difficult. Arrowslits and barbicans were added to the defenses, with many firing platforms built into the walls to allow large groups of archers to shoot. Some defenses included gatehouses with twin towers, which replaced older keeps as strong defensive points.

Despite these strengths, the castles and town walls are now known to have military weaknesses. The castles were much larger than needed to protect against Welsh attacks, but their size made it hard for the Crown to maintain or guard them properly. In some ways, the fortifications were too large, and historian Michael Prestwich noted that smaller projects might have been more effective. Rather than being scientifically designed, historian Richard Morris said the castles gave the impression of an elite group of soldiers, long-time companions of the king, creating grand military buildings with almost unlimited resources.

In the late 1900s and early 2000s, architectural research focused more on the castles’ roles as luxurious palaces and symbols of royal power. Each castle was designed to support the royal court if it visited. In the late 1200s, this meant having private rooms, service areas, and security, creating a royal palace in miniature. Some parts of these designs survive today; for example, Conwy has what historian Jeremy Ashbee calls the "best-preserved set of medieval private royal chambers in England and Wales," including a private garden for the queen. When built, the castles were more colorful than they appear today, matching 13th-century fashions. At Conwy, for instance, walls were white-washed with lime, and putlog holes in the walls may have held painted shields called targes.

The castles clearly showed Edward’s plan to rule North Wales permanently. They were often built on sites linked to former Welsh princes. Caernarfon, in particular, stands out for its use of colored stone, eagle statues, and polygonal towers. Historians have debated the meaning of these features. Arnold Taylor argued the design resembled the Walls of Constantinople, using imagery from the Byzantine Empire to show Edward’s authority. Abigail Wheatley later suggested the design was meant to link Edward to Roman sites in Britain, giving him a connection to Arthurian legends.

The Edwardian castles share architectural similarities with structures in Savoy, North Italy, built around the same time. Arnold Taylor first noted these similarities in the 1950s. Features like semi-circular door arches, window styles, corbelled towers, and crenellations with pinnacles appear in both Edward’s works in North Wales and Savoy’s castles, such as those in Saillon, La Bâtiaz, and Chillon. These similarities were once thought to be due to the influence of Master James of St George, Edward’s Savoy architect, who brought other Savoyard builders to North Wales.

However, early 21st-century research suggested Master James’ role and Savoyard influence may have been overstated. The stonework in North Wales is of higher quality than in Savoy, and key features like gatehouses are not found in Savoy. Research shows Master James likely managed projects rather than designed them, and some Savoy structures were built after he left. The similarities may instead result from the work of Savoy craftsmen and engineers, not a single person.

Beaumaris Castle was built near sea level using local Anglesey stone. The design included an inner and outer ward, surrounded by a moat now partially filled. The main entrance was the "Gate next the Sea," next to a tidal dock for direct sea supply. The dock was protected by a wall called the Gunners Walk and a firing platform that may have held a trebuchet. The outer ward had an eight-sided curtain wall with twelve turrets; one gateway led to the sea, and the other, the Llanfaes Gate, led to the north. The inner ward’s walls were stronger, with large towers and two big gatehouses. The inner ward housed accommodations and domestic buildings, with remains of fireplaces still visible in the stonework.

Historian Arnold Taylor called Beaumaris "Britain’s most perfect example of symmetrical concentric planning," and for many years, the castle was seen as the peak of military engineering during Edward I’s reign. UNESCO considers it a "unique artistic achievement" for combining "characteristic 13th-century double-wall structures with a central plan" and for the beauty of its "proportions and masonry."

Harlech Castle sits on a rock spur called the Harlech Dome, with steep land on the north and west. A ditch cut into the rock protects the castle’s approach. The castle has a concentric design, with inner and outer wards; the outer wall was originally taller. Built from local grey-green sandstone, the towers used large, regular blocks, while the walls used irregular material, possibly from the ditch. The main entrance would have involved crossing a stone bridge between two ditch towers and the main gatehouse, though little of the bridge remains today. A water gate overlooks a 127-step stairway leading to the foot of the cliffs.

The gatehouse has two large "D-shaped" defensive towers flanking the entrance. The passage into…