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Wales is full of castles and many of them hold interesting secrets that are otherwise left unknown. In this guide, I’ll reveal some of the most interesting facts about the castles in Wales and attempt to uncover some of their secrets.

If you’re planning a visit to Wales, you might also want to check out our full guide to the best castles in Wales.

1. Wales is the Castle Capital of Europe

There are 427 castles in Wales still standing or ruined and over 600 ever recorded. This makes Wales the castle capital of Europe with more castles per square mile than any other European country1 (source: Visit Wales).

2. Many Welsh Castles Were Not Built by the Welsh

Whilst a small handful of castles were constructed by Welsh lords, the vast majority were built by the English Kings and their lords. This was in an effort to fortify Wales and give the English control over the country. Because of this reason, many of the castles were involved in a long history of conflict and violence as the battle for power continued throughout much of history.

3. The Oldest Castle in Wales is Almost 1,000 Years Old

Whilst it is hard to pin down the oldest castle because there are a great number of variables involved in choosing such a structure, it is assumed by many that Chepstow Castle is the oldest still standing.

Chepstow was constructed in 1067 making it almost 1,000 years old. It was built by Earl William Fitz Osbern for William the Conqueror and was certainly one of the first stone castles built in Wales2 (source: CADW).

4. Wales is Home to the Second Largest Castle in Britain

The largest castle in Wales is Caerphilly Castle in the south of the country. Not only is it the largest castle in Wales but the second largest in Britain. The great fortress was built by the English in the 13th century and is still standing today. The turrets are open to climb and provide breathtaking views of the Welsh countryside3 (source: Visit Caerphilly).

5. Caergwrle Was the Last Castle Built by the Welsh

The last castle constructed in Wales by a native Welsh prince was Caergwrle Castle. The fortress was built by a man named Dafydd ap Gruffudd who was the brother of Llywelyn ap Gruffud. The Castle was built between 1278 and 1283 on land that had been presented to the Welsh Prince by Edward I4 (source: CADW).

6. Wales Is Home to the ‘Greatest Castle Never Built’

Wales is home to Beaumaris Castle which is also known as the ‘greatest castle never built’.

The construction of this massive fortress was begun by Edward I, King of England. However, work was halted prematurely due to a lack of funds and an increase in tensions with Scotland5 (source: Daily Post).

7. Abergavenny Castle Was the Site of a Gruesome Episode in Welsh History

On Christmas day, 1175 William de Braose, a Norman Lord, offered Sytsylt ap Dyferwald and the other Welsh Lords with whom he had been at war for years, a peace offering. The Welshmen came to the castle unarmed. Unfortunately, it was a trap and the Welsh were locked in and brutally murdered6 (source: South Wales Argus).

8. Some Welsh Castles Are a Protected UNESCO Heritage Site

Some of the castles in Wales have been made UNESCO heritage sites. This means they have been marked out for their importance and value. Currently, there are four Welsh Castles and town walls which have been granted this status, Caernarfon, Conwy, Beaumaris and Harlech, all of which were built by Edward I7 (source: UNESCO).

9. You Can Stay in a Castle in Wales

Some castles in Wales have been taken over and converted into hotels where you can stay! Some of these include Brecon Castle, Craig Y Nos Castle, Castell Deaudraeth, Plas Rhianfa, Cardigan Castle and Roch Castle. All of these offer a unique place to stay, particularly if being a lord or lady of a castle has always been your dream!

See our full guide to castles in Wales you can stay in for more inspiration.

10. Welsh Castles Have Been Featured in Film and TV

Many of the castles in Wales have been used as filming locations and this comes as no surprise considering their outstanding beauty! Perhaps the most famous recent example is Gwrych Castle in North Wales which was the location of I’m A Celebrity Get Me Out of Here because of COVID restrictions.

Penrhyn Castle was used in the filming of Watchmen and Kidwelly Castle also featured in the opening scene of Monty Python’s Holy Grail.

11. One Welsh Castle Took 47 Years and £20 Million to Build

Yes, you read that correctly! Caernarfon Castle took a staggering 47 years to build and cost £25,000 which is more than £20 million in today’s money. 

This is largely due to its impressive size which has also led to its inclusion on the UNESCO World Heritage list. Today it is recognised as one of the greatest buildings of the Middle Ages8 (source: CADW).

12. Some Castles’ Defences Have Been Reused and Repurposed

During the Second World War Cardiff was badly hit by bombing raids. In response to this, in 1939 the castle’s tunnels were used as air raid shelters for people who lived and worked in the city.

Because they had been built in a time when war and sieges were likely, the walls of the castle were extremely thick and well defended which therefore made them a great place for people to seek safety from the bombs.

13. The First Tudor King Was Born in Pembroke Castle

Pembroke Castle is the birthplace of Henry VII who ruled England between 1485 and 1509. Henry VII was born on the 28th January 1457 in one of the towers overlooking Westgate.

He would become the first Tudor monarch and gain his place on the throne when he beat Richard III at the Battle of Bosworth, an act which ended the Wars of the Roses9 (source: Pembroke Castle).

14. The Prince of Wales Is Usually Invested at Caernarfon Castle

On 1st July 1969, Prince Charles was invested in Caernarfon Castle. During the ceremony, the Prince of Wales had the coronet and robes placed on him and then he pledged allegiance to the Queen, HM Queen Elizabeth II. He spoke the words ‘I, Charles, Prince of Wales do become your liege man of life and limb’10 (source: Royal Collecton Trust).

15. One Welsh Castle is Haunted By an Opera Singer

If you are feeling brave, Craig Y Nos Castle in the Brecon Beacons has become known as the most haunted castle in Wales. The castle was brought by one of the most famous women in the world at the time, Adelina Patti who was an opera singer. She lived in the structure for 40 years and some claim her ghost still haunts the building which is now a hotel!

16. Edward I Was the Most Prolific Builder of Castles in Wales

Edward I was responsible for the construction of eight Welsh castles. Edward I lived between 1272 and 1307 and during that time he made several attempts to conquer Wales.

The first castle he built in the country was Builth Castle which he reconstructed after it was destroyed by Llywelyn in 1260. It is thought that Edward must have spent a fortune on the construction of all of these fortresses.

Molly is Wales Guidebook's expert on castles. She has a master's degree in history and studied at Swansea University where she learnt about Welsh history and it's many castles. Molly loves to get out and explore historical buildings in person, with Oystermouth, Cardiff, and Caerphilly Castles among her favourites. When not geeking out on castles, Molly likes to spend her time reading, exploring the countryside or in the gym.