Dinas Emrys is a medieval castle that overlooks Llyn Dinas in Snowdonia near Beddgelert. The current castle was built over the top of an ancient hillfort and sits on a strongly fortified rocky outcrop.

The castle started out as an Iron Age Hillfort. According to Welsh mythology, it was here that King Lludd ab Beli buried two dragons, one white and one red, which were to fight each other for all eternity. Modern archaeology reveals that Dinas Emrys was reoccupied in the late Roman period, since the rough stone banks around its western end date to this time. With the departure of Rome, chronicles from Nennius and Geoffrey of Monmouth tell the story of King Vortigern retreating into Snowdonia during his wars against the Saxon invaders and choosing this location as the place to build his seat.

Unfortunately for him, each night the ground was shaken and the fort collapsed by those same dragons from pre-Christian mythology. In the story, the king’s advisers tell him that a fatherless child has to be sacrificed in order to stop the fort from falling down. Myrddyn Emrys (known to us now as Merlin) explains instead that the Red Dragon represents the Britons and the White Dragon the Saxons. He prophesies that the Britons would be victorious over the Saxons since the red dragon kept defeating the white.

Archaeological evidence, including sherds of Eastern Mediterranean amphorae and Phoenician red slip dishes, all dating to the 5th and 6th centuries, indicate that Dinas Emrys was in fact occupied during Vortigern’s reign.

Today, the remains that are most visible were constructed by later Welsh kings and princes of Gwynedd between the 11th and 13th centuries. The fortifications at one time consisted of stone walls between eight to ten feet thick, which enclosed an irregular area of about 10 thousand square meters and included a rectangular tower.

The castle of Dinas Emrys is featured in The Last Pendragon Saga.