The castle features a large stone keep, which historian Richard Avent considers "the finest surviving example of a Welsh round tower".

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 northern Wales.

[3] 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.

[4] Llywelyn the Great initially controlled the princedom of Gwynedd, but grew more powerful throughout his reign, extending his influence over much of Wales during the early years of the 13th century.

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.

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.

[16] 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.

[16] Edward deployed 7,000 troops to detain Dafydd who was finally captured and executed in October; Dolbadarn was occupied by Norman forces.

[16] 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.

[19] 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.

[29] Dolbadarn Castle is featured on the cover of the album The Palms of Sorrowed Kings by American metal band Obsequiae, released in 2019.