In 1986, UNESCO recognized the Castles and Town Walls of King Edward in Gwynedd as a World Heritage Site. This cemented their place among the world’s most important historical sites and confirmed their status as the finest examples of late 13th—and early 14th-century military architecture in Europe. Their sheer size, precision, and brutal design make the Welsh castles of Edward I some of the most advanced medieval fortifications in history.
Even after 700 years, the castles stand perfectly preserved and are a chilling reminder of the brutal conquest that changed Wales forever. They were not built for beauty, but to intimidate, dominate, and destroy. Their massive stone walls, towering gates, and impenetrable defences make them a must-visit for anyone fascinated by medieval power and war.
Castles and Town Walls of King Edward in Gwynedd – The Fortress Network That Changed History
The Castles and Town Walls of King Edward in Gwynedd were never meant to protect a kingdom. They were designed to break one. After invading Wales twice in the 13th century, Edward I, the eldest son of Henry III refused to leave. Edward I knew the Welsh would never surrender, so he did something no king had done before.
With the help of James of St George, the greatest military architect of the time, Edward built a Ring of Iron around Wales. This unbreakable fortress system was so advanced that no army could take it down. The cost? A staggering £80,000, the equivalent of £56 million today – an unimaginable sum for the 13th century. No medieval king had ever spent so much on war. But Edward wasn’t just fighting a battle—he was erasing a nation’s resistance, one stone at a time.
These castles weren’t just strongholds; they were symbols of total control. They sent a message: England had won, and Wales would never be free again.
Edward’s Unstoppable Castle-Building Campaign
In just over two decades, Edward I reshaped Wales in stone. From 1277 to 1330, he constructed or reinforced 17 castles, creating the strongest castle network Europe had ever seen. North Wales was the greatest threat to English rule, so he poured his resources into securing it. Four of Edward’s castles became the most famous—Beaumaris, Caernarfon, Conwy, and Harlech. Today, they are UNESCO World Heritage Sites, perfectly preserved after centuries. But they were only part of a network that stretched across North Wales, locking the land under English control.
These fortresses had water gates, allowing them to resupply by sea. No Welsh rebellion could ever cut them off.
1. Caernarfon Castle
Why did Edward I build here? He could have chosen anywhere. But he picked a site the Romans had already claimed a thousand years earlier. He wasn’t just building a castle—he was linking himself to the Roman Empire, which had ruled the world.
In 1283, the work at Caernarfon Castle began. 47 years later, it still wasn’t finished. Edward’s brilliant master and military genius, James of Saint George, led an army—not of soldiers but builders. They came from across England to create a fortress-palace like no other. Inspired by the mighty walls of Constantinople, its design struck fear into anyone who dared to challenge the king.
Edward I built more than a castle—he built control. The town below wasn’t for the Welsh. He filled it with English settlers who lived behind walls, keeping the Welsh outside and under his rule.
Construction was shockingly expensive. Between 1283 and 1330, Caernarfon and its town walls with towers, gates and multi-arched bridge approach, swallowed between £20,000 to £25,000. This sum would be over £17.5 million in today’s money. Yet, despite the vast fortune spent, it was never truly finished. By the 1330s, the threat of Welsh rebellion had faded. Edward’s successors had little interest in pouring more money into the project and abandoned it.
THE BIRTH OF A PRINCE
Edward I didn’t just build Caernarfon to control Wales—he used it to rewrite history. In 1284, just one year after the castle’s construction began, his wife, Queen Eleanor, gave birth here. Their son, Edward of Caernarfon, became the first English Prince of Wales. A title that still belongs to the English monarchy today.
CAERNARFON TODAY
Centuries later, Caernarfon played another royal role: In 1969, it hosted Prince Charles’s investiture. Today, Caernarfon Castle is a UNESCO World Heritage site, part of the Castles and Town Walls of King Edward in Gwynedd. It remains one of the most powerful symbols of history. It’s one of the most striking buildings of the Middle Ages and one of the most famous castles in Wales.
2. Conwy Castle
Before Edward I built the town of Conwy, this land housed a Cistercian monastery and a Welsh royal palace. He replaced them with Conwy Castle and its fortified town. This way the king erased Welsh history, and replaced it with a new English order.
The king arrived at Conwy in the middle of March 1283, and the construction of the castle began immediately. But Edward didn’t stop there; he enclosed a brand-new English town within 1.3 km of walls. Inside, English settlers thrived there, protected by massive stone walls.
The works on this impressive defensive stronghold were paralleled at Caernarfon and Harlech. This trio of fortresses overshadowed even those recently built at Flint, Rhuddlan, and Aberystwyth.
COSTLY FORTRESS
Again, this was no cheap project, overseen by none other than Master James of St. George. In just 4 years, the castle and its towers cost an astonishing £15,000 – a fortune beyond imagination, at the time. The result? The castle’s eight massive towers, two barbicans, and towering stone walls overlooked a key crossing on the River Conwy. It had the earliest stone machicolations in Britain, allowing defenders to rain down destruction on enemies below. A secret gate leading to the water ensured it could be resupplied by sea if attacked. Conwy Castle even faced wars. It withstood the 1294 Welsh uprising and became a stronghold during the 1401 Glyndŵr Rebellion. Even King Richard II sought refuge behind its walls in 1399.
More than 700 years later, Conwy Castle remains one of the finest medieval fortresses in Europe. Historian Jeremy Ashbee had described it as the ‘best-preserved suite of medieval private royal chambers in England and Wales. Today, the castle’s high curtain walls and spiral staircases allow you to walk its battlements, standing where Edward’s knights once stood. UNESCO recognizes it as part of the Castles and Town Walls of King Edward in Gwynedd, cementing its place in history.
3. Harlech Castle
No other stronghold built by King Edward I sits in a more breathtaking location than Harlech Castle. This Grade I listed medieval fortification stands on a rocky outcrop near the Irish Sea, overlooking the peaks of Snowdonia. Harlech’s walls weren’t just thick; they used the rocky terrain as an extra defence.
After Edward crushed Welsh resistance at Castell y Bere, his army marched to Harlech in 1282. He ordered Harlech built immediately.
BUT WHY HERE?
The location has deep roots in Welsh legend. It was said to be the home of Branwen, a tragic princess from mythology. No evidence of an earlier Welsh fort exists, but the location’s strategic importance was undeniable. The English king wasn’t interested in legends—he just wanted a fortress that could withstand attack and command North Wales.
POWER, CONTROL, AND FEAR IN STONE
James of St George designed it with a revolutionary ‘walls within walls’ defence. Even if attackers broke through the first layer, they’d face another. And the legendary watergate—a steep, hidden stairway leading down to what was once the sea. In medieval times, supplies could be smuggled in during a siege. It took just seven years (1282-1289) to build, thanks to 227 masons, 546 labourers, and dozens of blacksmiths and carpenters. The king spent a fortune—£8,190—on its construction. It was a significant part of his £80,000 campaign that created the Castles and Town Walls of King Edward in Gwynedd.
But even the strongest walls have their breaking point. In 1404, Owain Glyndŵr took Harlech, making it his final base in his rebellion against the English. Later, during the Wars of the Roses, Lancastrians held out for seven years. Their defiance inspired the Welsh folk song Men of Harlech, still sung today.
4. Beaumaris Castle
After conquering North Wales in 1282, Beaumaris Castle should have been the jewel of Edward I’s Ring of Iron. Instead, it was the last to begin and became a brutal lesson in overspending.
How did this happen?
Edward first thought of building Beaumaris in 1284, but funds ran out after he spent too much money on other castles. Only after the Welsh rebelled in 1294, he was forced to act. The work started in 1295 under James of St George, who had already designed other Castles and Town Walls of King Edward in Gwynedd.
THE CASTLE THAT RAN OUT OF MONEY
Work began fast and the costs were unbelievable. 1,800 workers, 450 stonemasons, and 375 quarriers worked on the site. They burned through £270 per week—so much that the king soon had to pay workers in leather tokens instead of coins. By 1300, Edward had poured over £11,000. Beaumaris was only partially complete, with the inner walls and towers standing only half as high as planned.
Then something else happened: Edward’s attention turned to Scotland. His war there drained money, cut the funding, and work at Beaumaris stopped. In 1306, fears of a Scottish invasion forced him to restart construction, but by 1330, he abandoned Beaumaris—leaving it unfinished forever. The king invested £15,000 in the fortress, but the work stopped before completion. Yet, even in its unfinished state, Beaumaris remains a masterpiece. Historian Arnold Taylor called it Britain’s most perfect example of symmetrical concentric planning. UNESCO agrees, describing it as a ‘unique artistic achievement’ with its double walls and perfect symmetry.
Now you know what four of the most famous castles and town walls of King Edward in Gwynedd are!
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