Beaumaris Castle: Concentric Castle Perfection, on the Welsh Isle of Anglesey

The Welsh Flag

Beaumaris Castle, on the isle of Anglesey, Wales, is the most impressive example of a concentric castle in the world.

It's a formidable, symmetrical little fortress - created by Edward I of England who, in a fit of rage, sought to dominate the Welsh.

From 1285 onwards, he poured huge amounts of money into building an 'iron ring' of castles across the coast of North Wales.

Beaumaris, then, is a sister to Edward I's other Welsh fortresses - which include Caernarfon, Conwy, and Harlech. It was the last to be built, and, in some ways, is the piece de resistance of Edward I's frenzied work.


Hey - I'm Edd.

I've always loved visiting amazing old castles.

I've created this site to share my favourites.

If you're enjoying this website, don't miss my beautiful new hardback book!

Beaumaris Castle Aerial View An aerial view of Beaumaris Castle, which use demonstrates its perfect concentric layout. This is reproduced under the UK Open Government License.

Concentric Perfection: Beaumaris Castle's Perfect, Symmetrical Layout

The genius behind Beaumaris Castle - and the majority of Edward I's Welsh castles - was the architect Master James of St George. Master James had masterminded the mighty towers of Harlech Castle, and the walls of Caernarfon which wrap around the town and the castle, too.

Edward I almost certainly chose the site for Beaumaris Castle in about 1285 - at the same time that he selected the locations Harlech and Conway castles.

However, for strategic decisions - and sheer financial pressures - he started building those first. As a result, when it came to building Beaumaris in about 1295, Master James had learned a great deal from those neighbouring castles.

Beaumaris Castle View of Moat Beaumaris looks a bit like how a castle 'should' look: crumbling towers surrounded by a deep moat. Credit: Denis Egan, CC-BY-2.0.

Beaumaris was to be built on flat, marshy land (beau-marys literally means 'fair marsh') adjacent to the Irish sea. In Harlech castle, Master James' design had been restricted by the need to build the castle on an uneven, rocky outcrop. Here in Beaumaris, on flat land, he could experiment with size and shape to his heart's content.

Master James had also learned lessons from his work upon coastal Caernarfon. He planned an ingenious system of docks and water-gates, to allow ships to supply Beaumaris in the case of siege.

You can see this in the present 'docking gate', which is adjacent to the modern ticket office. Ships carrying as much as 15 tonnes of cargo could unload from there. In addition, Master James devised a deep, symmetrical moat, designed to be filled by the incoming tides.

Beaumaris Castle Moat About two thirds of the castle moat survives to today. The remainder was filled in in the c19th. Credit: Stuart, CC-BY-2.0.

The level of planning which went into Beaumaris was matched by its phenomenal expense and labour cost.

In the late 1290s, more than 2,000 men worked simultaneously upon this mighty castle. The overall sum expended on the (incomplete) castle was £15,000 - an insane amount, given that the entire annual income for the English treasury was less than £20,000 per year.

Beaumaris was, really, a vanity project for Edward I - a ruthless king fixated upon gaining control of Wales.

Beaumaris: The Delicacies of the Concentric Castle Design

A Plan of a Concentric Castle - Beaumaris, Wales A Plan of Beaumaris, which illustrates the concentric symmetry of the castle.

The style of Beaumaris is best described as a concentric design, or "a castle within a castle". It's made up of a phenomenally strong, 4.7m thick outer curtain wall which encircles the equally well-defended inner castle.

In actual fact, Beaumaris is undoubtedly the world's best example of concentric castle design.

It was a method of building which maximised the castle defences. First of all, the outer concentric wall was shorter than the inner to give archers a vantage point against oncoming enemies.

This design was meant to make the castle almost impregnable. Even if attackers managed to overcome the outer defences, the 'dead space' space between the outer and inner walls would have been an extremely dangerous place to be.

Indeed, there were 164 arrow-slits in the inner wall, designed so arrows could be fired at trespassing intruders from almost any direction.

The outer curtain wall contains an almost-symmetrical ten towers; and the inner wall wraps around six formidable stone towers and also the North and South gatehouses. The moat would have circled round the entire fortress, although it's been partially filled-in today.

Reflections of Beaumaris Castle Throughout Beaumaris, there's a pervasive sense of orderliness and symmetry. This photo, through the barbican at the entrance, captures this nicely. Credit: Denis Egan, CC-BY-2.0.

The only route of access into the castle would have been through the barbican to the South gatehouse - which contained more than 15 lines of defence, including a drawbridge and multiple portcullises.

Beaumaris Castle: Destined to Always Be Unfinished

Beaumaris was Edward I's most ambitious - and technically difficult - project. And it was never completed. Although the main parts of the castle were built extremely quickly (works began in 1295 and ended in 1330), the towers, gatehouses and defences were never finished.

Beaumaris Castle Looking onto the sizeable castle gatehouse. Credit: Vix B, CC-BY-2.0.

That's quite apparent when you visit the the castle today. On approach, you'll notice that Beaumaris is quite a squat little fortress. All its towers are quite short and dumpy, and, from a distance, it doesn't quite look as impressive as you'd imagine from the aerial photos.

If the castle had been fully finished, its modern appearance might have been much grander. The two round towers which flank the Northern gatehouse are the tallest in the entire castle, but even these are about 10m shorter than they were meant to be - they lack battlements and the intended roofing.

Beaumaris Castle Another intricately carved stone archway in the castle. Credit: Jam RolyPoly, CC-BY-ND-2.0.

All the other towers in the internal ring of the castle are about half the height planned. The original designs crowned them with grand turrets which would have given the castle a very distinctive skyline.

To top it off, the gatehouse, at the front of the castle, looks formidable; but the original plans would have given it a second storey of rooms and fortifications, effectively doubling its height.

The Northern gatehouse, which stands opposite, was meant to span the same size, too. What you see today is undeniably impressive: but it could have been much stronger still.

So, why was Beaumaris Castle left unfinished? It was partly due to the death of Edward I in 1307, and of architect Master James of St George in 1309. But it was more than that. Both died on the borders of Scotland - showing that Edward's attentions were then more fixed upon conquering the Scots than controlling the Welsh.

Beaumaris Castle Window detail within the castle. Credit: Jam RolyPoly, CC-BY-ND-2.0.

Strategically, too, Beaumaris was placed outside of the action. From the 1300s onwards, the majority of Welsh/English squirmishes had ended - and any smaller areas of resistance were centered around Harlech and Conwy.

Building and strengthening Beaumaris was no longer a priority. Consequently, the castle was begun in 1295 and left unfinished from 1330 onwards - a tiny lifespan.

One of the World's Strongest Castles... Ironically Never Attacked

Ironically, given its phenomenal, defensive potential, Beaumaris' strength was never really called into question.

The castle suffered no significant siege until 1403, where it was briefly occupied by the Welsh rebellions lead by Owain Glyn Dwr. Their rebellion was swiftly overturned in 1405.

It's perhaps ironic that the most impressive concentric castle in the world never had to prove the value of its own design. It's also somewhat sad that the mighty plans of Beaumaris were never fully realised. Effectively the castle is but a blueprint of what it could have been.

Sadly, too, Beaumaris was passed over during the 1800s.

During this period, writers and painters of the Romantic movement used the decaying remains of once-proud castles as inspiration for their art and poetry - Turner painted the decaying walls of both Conwy and neighbouring Caernarfon. Beaumaris, however, remained perpetually isolated from the main action - alone and ivy-covered, huddling on Anglesey.

Beaumaris Castle Killer Birds I could't stop gigging after seeing this modern warning sign in the castle. What on earth does the image on the right end mean? Beware of killer birds?! Credit: Dave Younce, CC-BY-2.0.

Today, happily, Beaumaris Castle is under the care of CADW and is a designated UNESCO World Heritage Site. It's a brilliant little place to visit, but it's still somewhat forgotten by tourists. The only thing I can do is to urge you to go discover it yourself - you may be one of the few people exploring it that day.

If you've found this page on Beaumaris Castle interesting, do read about the other fortresses in Edward I's Iron Ring of North Wales. I've written pages on both Harlech Castle and also Caernarfon Castle, too.

Discover more cunning plots, dusty legends, and tales of England's most beautiful castles...

What lurks in the bedrock beneath Dover Castle?

Where might you find a surviving Round Table, and what happened to 'King Arthur's Corpse' at Tintagel?

What exactly was so terrifying about Medieval machicolations?

And was it a terrible accident, or was Lady Amy Dudley murdered?

If you'd like to delve into these mysteries - and discover many more - you'll love my first print book, Exploring English Castles.

In the words of the American Library Association, it's a 'big, luscious book'.

It's filled with stories, secrets, fables and photos, and runs to 272 pages with more than 200 colour photographs.

It's available from all good bookstores in the US, Europe, Canada and Australia.

Click to buy 'Exploring English Castles'!