Dolbadarn Castle Dolbadarn Castle is a fortification built by the Welsh prince Llywelyn the Great during the early 13th century , at the base of the Llanberis Pass , in North Wales . The castle was important both militarily and as a symbol of Llywelyn ' s power and authority . The castle features a large stone keep , which historian Richard Avent considers " the finest surviving example of a Welsh round tower " . In 1284 Dolbadarn was taken by Edward I , who removed some of its timbers to build his new castle at Caernarfon . The castle was used as a manor house for some years , before falling into ruin . In the 18th and 19th century it was a popular destination for painters interested in Sublime and Picturesque landscapes . It is now owned by Cadw and managed as a tourist attraction . History . 1220 – 40 . Dolbadarn Castle was built in either the 1220s or the 1230s by Llywelyn the Great , at the base of the Llanberis Pass , overlooking the lake of Llyn Padarn in North Wales . Traditionally the Welsh princes had not constructed castles , instead using undefended palaces called " llysoedd " , or courts . From the late 11th century onwards , the Normans had advanced into Wales , taking lands in the north and establishing a band of occupied territory in the south called the Welsh Marches . During the 12th century some timber and earthwork castles began to be built , but in small numbers . Llywelyn the Great initially controlled the princedom of Gwynedd , but grew more powerful over the course of his reign , extending his influence over much of Wales during the early years of the 13th century . Llywelyn was faced by several challenges , including dealing with the threat from the kings of England , and maintaining his authority over the native Welsh . As part of this strategy , Llywelyn built Castell y Bere , an innovative stone Welsh castle , in the 1220s . Shortly afterwards he began the first phases of Dolbadarn Castle , constructing the initial stone fortifications on the site , including two square stone towers . The location of the castle was important both because it controlled an important mountain pass , and possibly because Llywelyn claimed authority as the lord of the mountains and coasts of Wales : several of his castles appear to have been located with such political symbolism in mind . It is also possible that Llywelyn may have built his castle on top of the remains of a previous fortification constructed by Maelgwn Gwynedd , a king of Gwynedd in the 6th century , although no such remains have been found . As part of his strategy for dealing with the Marcher Lords , Llywelyn married his eldest son , Dafydd , to Isabella , the daughter of William de Braose , a powerful lord in Brecon , Builth and Abergavenny . The Marcher Lords had adopted a style of stone castle that included circular keep s and an integrated system of curtain walls . Following Dafydd ' s marriage , Llywelyn appears to have started a second phase of building at Dolbadarn , probably in the 1240s , adding these elements to the existing castle . The prince was probably aiming not only to incorporate the latest military technology , but also to create a castle of equal prestige to those of his new allies in the south . Traditionally the surrounding district of Is Gwyrfai had been run from the town of Llanbeblig ; after the 1240s , this role was transferred to Dolbadarn . 1240 – 1300 . Following Llywelyn ' s death in 1240 , Gwynedd ' s power declined and many of its eastern lands were taken by Henry III of England in 1247 . Llywelyn ' s grandson , Llywelyn the Last , took power in 1255 and imprisoned his brother Owain ap Gruffudd before extending his power across Wales . Owain was eventually released in 1277 and there has been much historical debate over which castle he was held in . Hywel Foel ap Griffri wrote a famous poem describing Owain ' s long imprisonment in a round tower ; historians believe that this refers to the keep at Dolbardarn . The conflict between the Welsh princes and the English kings continued in the reign of Edward I . In 1282 Llweyln fought a final campaign against Edward , ending in the prince ' s death near Builth that December . His brother , Dafydd ap Gruffydd , assumed power but during 1283 was forced south into Snowdonia and by May his government was based from Dolbadarn Castle . Edward deployed 7 , 000 troops to detain Dafydd who was finally captured and executed in October ; Dolbadarn was occupied by Norman forces . Edward was determined to prevent any further rebellion in North Wales and set about building a sequence of new castles and walled towns , replacing the old Welsh administrative system with a new principality governed from Caernarfon . Dolbadarn was no longer relevant and within two years timber from the castle was being used by the Normans for the construction of Caernarfon Castle . This was both a practical and a symbolic action , demonstrating Norman power over one of the most important possessions of the Welsh princes . 14th – 21st centuries . The remaining parts of the castle continued to be used as a manor house into the 14th century . By the 18th century , however , Dolbadarn Castle was ruined and uninhabited . From the 1760s onwards , however , it became a popular topic for painters interested in the then fashionable landscape styles of the Sublime and the Picturesque . Typically the castle was painted in the middle ground , allowing the viewer ' s eye to contrast its ruined outline with the lakes and mountains of Snowdonia ; frequently the landscape was misrepresented by the artist , to create a more striking or dramatic effect . J . M . W . Turner ' s 1802 work depicted the back - lit castle looming over the landscape and became particularly famous , but the paintings of the castle by Richard Wilson and Paul Sandby also represent important artistic works of the period . In 1941 the castle was given to the State by Sir Michael Duff . It is now maintained by Cadw and is protected as a Grade I * listed building and as a scheduled monument . In the light of Welsh devolution and other political changes , the history of Dolbadarn Castle and similar Welsh castles has become increasing prominent . In response , Cadw have noted that they intend to give an increased priority to communicating the history of these castles and the Welsh princes . Architecture . Dolbadarn Castle comprises a courtyard , surrounded by a number of towers and a round keep . The castle is built from purple and green slate stone , mainly constructed in a dry stone fashion without mortar , with the exception of the keep . The courtyard follows the natural shape of the hill and is protected by a curtain wall ; originally perhaps 15 feet ( 5 m ) high , it is now only at most 3 feet ( 1 m ) high . Of the castle buildings , only the keep remains to any significant height . The keep today is 46 feet ( 14 m ) high and is modelled on early 13th - century English round towers built in the south of the Welsh Marches . As with other Welsh - constructed towers , the entrance is on the first storey , not at ground level ; it may originally have been protected by a porch . The keep had a portcullis which would have been drawn up past the window on the second storey of the tower . While the castle ' s flooring has long since disappeared , its interior staircase to the upper storey may still be climbed . This second storey would have formed the main chamber in the keep and had a large fireplace and a latrine . Originally the keep would have had a parapet and battlements , since destroyed . Historian Richard Avent considers it " the finest surviving example of a Welsh round tower " . The rectangular west tower was a relatively short defensive structure , designed to protect the more vulnerable western slope of the ridge . A similar tower in the south overlooks the entrance to the castle . At the north end of the castle is the hall , stretching across the courtyard ; in the east corner is an additional building , probably built by the English at the end of the 13th century . Although the hall is relatively large , 50 by 27 feet ( 15 by 8 m ) , these buildings follow a simpler design to those current in England at the time , where a combination of a hall , chamber and a service block in castles was becoming more common .