The comprehensive gazetteer and bibliography of the medieval castles, fortifications and palaces of England, Wales, the Islands.
The listings
Other Info
Print Page 
Next Record 
Previous Record 
Back to list 

Degannwy Castle

Also known as, or recorded in historical documents as;
Castle of Gannoc; Gannock; Dagaunoth; Deganwy; Hegannow

In the community of Conwy.
In the historic county of Caernarfonshire.
Modern authority of Conwy.
Preserved county of Gwynedd.

OS Map Grid Reference: SH78227945
Latitude 53.29786° Longitude -3.82833°

Degannwy Castle has been described as a certain Timber Castle, and also as a certain Masonry Castle.

There are masonry footings remains.

This site is a scheduled monument protected by law.
This is a Grade 2* listed building protected by law*.


Fragmentary shattered ruins of a great stone-built fortress crown the twin peaks of Deganwy Castle. This was Arx Decantorum, the seat of Maelgwn tyrant of Gwynedd in the sixth century, burnt by lightning in 812 and destroyed by the Saxons in 822 AD (see NPRN 404377). In the late eleventh century this was the seat of Robert of Rhuddlan from which he levied extortion on Gwynedd and from which he rode out to his death. As the Castrum de Gannoc it changed hands, was rebuilt and destroyed throughout the thirteenth century. The visible ruins are those of the great castle, accompanied by a borough, built by Henry III in 1245-50 that was beleaguered for seven years before being systematically destroyed by Llywelyn ab Gruffudd in 1263. Some activity continued at the site and the borough was still active in 1305. The castle was excavated in 1961-6, when evidence was recovered for a later prehistoric style fortress on the western peak, along with first to third century Roman material. The main castle court occupied the western crag and enclosed an area about 60m across. It included at least one great round tower and several domestic blocks. The smaller eastern crag was crowned by the irregular Mansel's Tower. The area between the crags was enclosed by great ramparts and walls, with a monumental twin-towered gatehouse on the south-side. Extensive settlement earthworks to the north and south of the castle (NPRN 400533, 400535) may represent several periods of occupation, including the thirteenth century borough (see NPRN 400533). The name attached to this area, 'the Vardre', suggests that it was at some time a bond settlement associated with a local court. (Coflein–John Wiles 27.07.07)

Set across 2 steep hills known as The Fardre inland from the village, with panoramic view across Conwy, estuary, coastline and N Wales mountains.
Although it was a defended site from the early medieval period, extant masonry remains of Deganwy Castle belong to building campaigns of the C13, during which time it was held alternately by both Welsh and English forces. The earliest part of the present structure is the revetment on the N side, of c1213 built by Llywelyn ap Iorwerth. The remainder of exposed masonry was added in the period 1245-54, when the castle was substantially rebuilt by Henry III, but not completed. It was captured in 1263 by Llywelyn ap Gruffudd. When Edward I seized control over the area in 1283 he chose not to rebuild Deganwy but to build a new castle at Conwy.
A fortification between 2 steep hillocks, with bailey between them. The former S entrance retains a short section of rubble-stone wall close to the former gatehouse, and other footings of the wall are also visible. On the N side is a bank and ditch, and a short section of a rubble-stone wall at R angles, probably part of a gateway, although the N wall was never completed. The W hillock retains traces of mid C13 curtain wall to the S and E, with a more substantial earlier surviving section to the NW corner. Here there is the base of a round turret and, at a lower level, a substantial retaining wall, both of coursed rubble stone. No structures are now visible on the E hillock, where Mansells Tower formerly stood. (Listed Building Report)

The monument comprises the remains of Degannwy Castle which occupies a commanding position about 1/4 m E of the mouth of the River Conway. The fortifications occupy two precipitous hillocks separated by a saddle. Few of the visible remains are likely to be earlier than the 13th century, but the site has a long history. Coins and a scrap of pottery indicate occupation during the Roman period. Late traditions make it the Llys of Maelgwn Gwynedd, and it is mentioned as ‘Arx Decantorum’ in 822. In c.1080 a castle was built here by Robert of Rhuddlan. The district was subsequently recovered by the Welsh, and in 1200 passed by inheritance to Llywelyn Fawr. The castle was destroyed in 1210 in the face of an English advance, refortified in timber by the Earl of Chester, and recaptured in 1213 by Llywelyn. In 1241 his son David once again destroyed the castle in preparation to resist an attack by Henry III, to whom the site was transferred as part of the peace terms. In 1244, the conflict was reopened, and the King ordered that the castle of ‘Gannok’ should be fortified, but the initial successes of the Welsh prevented much progress until he himself reached the site, where he remained from August to October of 1245. The castle was again attacked by Llywelyn ap Gruffydd in 1257, and was captured and probably finally destroyed in 1263. Of the four or five periods of construction for which there is this documentary evidence, only two, both probably of the 13th century, can be identified on the site with any certainty. It is probable that the earlier works were all of earth, timber and dry stone, and those they were either reshaped or obliterated by the later structures. The rubble masonry is built of the local rhyolite forming the two hillocks; the fragments of dressed stone are of imported grit. The fortified area falls into three parts. The Donjon occupies the larger (W) hill, Mansell’s tower stands on the E hillock, and the Bailey occupies the saddle between. Architectural Description: The Donjon of the mid-13th-century castle consisted of a polygonal enclosure wall about 4ft thick round the top of the hill. Near the NW angle are two latrine slots. The SW angle, at which the entrance lay, is destroyed. At the SE angle stood a round tower about 40ft in diameter with a simple roll moulding at its base - almost certainly the ‘tower of the castle’, built in 1247 and raised one storey in 1248. To the W of this lie the remains of a range of substantial buildings about 90ft by 30ft, including the King’s Hall, which was completed by 1250. At the E end of these and on a different orientation can be seen the angle of a rectangular building, perhaps part of the castle of 1213-41. To that period also may belong the revetment wall on the N side of the hill, which appears to be earlier than the main enclosure wall. The large quarry near the centre of the hill and the S end of a rectangular building E of it are ancient, but of uncertain period. The Donjon was approached up a steep roadway rising from E to W along the S side of the hill, with a gate at each end. The track was bounded above by a revetted slope and below by a vertical revetment wall. The S side of the Bailey is protected by a wall about 5ft thick with a ditch outside. Midway between the two hills are the remains of a strong gateway, with a passage about 8ft wide between a pair of D-shaped towers, each about 45ft by 30ft. Near the foot of the E hill a tower about 12ft square stood within the wall. Below it there appears to have been a latrine outlet, and higher up the hill the base of a small turret projects from the wall. On the N side of the bailey the only surviving masonry is a short stub of walling just below the enclosure wall on the W hill, and a substantial fragment which seems to have been intended to form part of a gateway. Apart from these, the defences on this side are composed merely of a strong ditch and an earthen bank which seems never to have carried any masonry. It was originally intended that the defences of the bailey should be completed in stone as on the S side. On August 23, 1250, instructions were sent to Alan la Zusch to raise Mansell’s tower by 12ft, to fortify the bailey of the castle between that tower and the donjon with stone and lime, and to make a barrier (incinctorium) outside the tower, two gates with two towers on each side in pairs, two suitable chambers above these towers, with fireplaces, and a chapel in the town of ‘Gannoc’ in honour of the Blessed Virgin. But in the Pipe Roll for 1250-4 payment is recorded for walling half the bailey and making one such gate. It seems clear that work on the N side was never more than started, and that very little further work was done on the fortifications. Mansell’s Tower (on the E hill) now appears as a low wall, D-shaped in plan. It seems probable that the W side was originally closed. A platform a little below the top of the hill on the E side may be the remains of unfinished work for the ‘barrier’. Outside the main enclosure are various earthworks. The gates on both sides of the bailey are approached by roadways slanting up the hillside. On the S of the W hill and on the N of the E hill are levelled platforms which seem to have carried rectangular buildings of uncertain age and purpose; and N of the bailey is a group of roughly rectangular enclosures sometimes associated with traces of long huts. These last may perhaps be the remains of the town, which received its charter in 1252 and from which a rent of 10 shillings is recorded in the Pipe Roll for 1250-5. A millstone, 1ft 5ins in diameter and 3ins thick, having a central hole 3.5ins in diameter with two radial slots, was exposed just outside the S gate of the bailey in 1948. The construction of a horse mill was ordered in 1250. The remains of the associated settlement are visible north and south of the castle as various bumps and hollows. (Scheduling Report)

It has been suggested that Edward I used the stones of Deganwy to build his new fortress of Conwy although it perhaps more likely that large structural timber, lead and other such, rather than stone was taken. The paltry ruins which can be seen today are mostly from Henry III's fortification, and include the foundations of the gatehouse towers, traces of curtain wall, and the bailey ditches and banks.
Links to archaeological and architectural databases, mapping and other online resources

Data >
Coflein   County HER   Scheduling   Listing    
Maps >
Streetmap   NLS maps   Where's the path   Old-Maps      
Data/Maps > 
Magic   Historic Wales   V. O. B.   Geology   LIDAR  
Air Photos > 
Bing Maps   Google Maps   Getmapping   ZoomEarth      
Photos >
CastleFacts   Geograph   Flickr   Panoramio      

Sources of information, references and further reading
Most of the sites or buildings recorded in this web site are NOT open to the public and permission to visit a site must always be sought from the landowner or tenant.
It is an offence to disturb a Scheduled Monument without consent. It is a destruction of everyone's heritage to remove archaeological evidence from ANY site without proper recording and reporting.
Don't use metal detectors on historic sites without authorisation.
The information on this web page may be derived from information compiled by and/or copyright of the Royal Commission on the Ancient and Historic Monuments of Wales, the four welsh archaeological trusts and other individuals and organisations. It may also contain Designated Historic Asset Descriptive Information from The Welsh Historic Environment Service (Cadw), licensed under the Open Government Licence. All the sources given should be consulted to identify the original copyright holder and permission obtained from them before use of the information on this site for commercial purposes.
The author and compiler of Gatehouse does not receive any income from the site and funds it himself. The information within this site is provided freely for educational purposes only.
The bibliography owes much to various bibliographies produced by John Kenyon for the Council for British Archaeology, the Castle Studies Group and others.
Suggestions for finding online and/or hard copies of bibliographical sources can be seen at this link.
Minor archaeological investigations, such as watching brief reports, and some other 'grey' literature is most likely to be held by H.E.R.s but is often poorly referenced and is unlikely to be recorded here, or elsewhere, but some suggestions can be found here.
The possible site or monument is represented on maps as a point location. This is a guide only. It should be noted that OS grid references defines an area, not a point location. In practice this means the actual center of the site or monument may often, but not always, be to the North East of the point shown.
Locations derived from OS grid references and from latitude longitiude may differ by a small distance.
Further information on mapping and location can be seen at this link.
Lidar coverage in the UK is not complete. The button above will give an idea of the area of coverage. Higher resolution lidar images in both DSM and DTM form may be available from Lle A geo-Portal for Wales (click the preview tag to bring up a map and then select format byclicking on the small blue diamond in the top right corner of the map.)
Please help to make this as useful a resource as possible by contacting Gatehouse if you see errors, can add information or have suggestions for improvements in functality and design.
Help is acknowledged.
*The listed building may not be the actual medieval building, but a building on the site of, or incorporating fragments of the described site.

This record last updated 28/06/2017 18:13:03