Dinas Emrys is a mysterious rocky, steep-sided and partly tree-covered hill, overlooking the beautiful lake called Llyn Dinas and is a dominating landmark in the area.

Evidence exists of human occupation on Dinas Emrys dating from the late Iron Ages. There have been successive settlements there since that time, the latest being in the 12th century. There is evidence of a pool at the base of the tower but this dates from a medieval dwelling. The are many walls still visible from mixed periods and it can be visited today, but only with a National Trust guide, such is it's fragility.

Dinas Emrys is famed for it's connection to the tale of Vortigern and Merlin, this tale appears in many medieval sources in various forms. It's first full form seems to be in Nennius's 9th century book the Historia Brittonum.

The story tells how Vortigern defeated and fleeing from the Saxons comes westward to a part of Gwynedd where the landscape forms a remarkably easily defensible knoll. Here his druid advisers tell him to build a castle. The building is ill-fated, as every night the walls collapse and no progress is made. In the end a human sacrifice is called for and a boy with no earthly father is required for this role. Here Merlin (known also as Emrys) enters the tale. But the young Merlin's powers are such that rather than being sacrificed he finds the root cause for the constant collapse. Beneath the hill, in a pool, two dragons, one red and one white were locked in eternal battle. Each night they fought, the white one driving the red to exhaustion but the red recovering and finally driving the white away. The dragons were interpreted by Merlin to mean the Saxons (white) and the British (red), and Merlin prophesied the coming of Arthur Pendragon, who would drive them out. Such was Vortigern's gratitude the newly built castle was named after Merlin (Emrys) and Merlin given the fort, Vortigern being advised by Merlin to build a new one elsewhere.

Vortigern is a character long confused in history. Were his origins from other Irish tales and used to explain political events of the time? Or was he indeed a British king who invited in the Saxons and out of some misdeed was brought to a sad end? Was his name tied to a saint? There are many questions and time has concealed the answers.

The name Dinas Emrys is thought to be a later name for the site, the original probably Dinas Ffaraon or Dinas Ffaraon Dandde, meaning fort of the pharaoh or fort of the fiery pharaoh. This is from a tale related in the Mabinogion (historically written much later but acknowledged to contain vestiges of much older tales), in which a red dragon/serpent's head is buried under the fort. This could indicate it was a site of a powerful lord and indeed it has been suggested the origin of the name Emrys may be Emyr (which can be taken to mean lord or king). Emrys is taken as being Welsh for Ambrosius and so connected to another famed lord.

How Merlin becomes involved in the tale is very confused too. He is connected by the name Emrys and so to Ambrosius. There is also a possibility that at the time the tale took it's final form the change from the Celtic Church to the Anglo-Roman church had a part in it's shaping. The old Celtic Church was far more tolerant of older British pagan beliefs having absorbed them whilst the Roman one left much of them behind. Vortigern was essentially regarded as Christian (especially through the saintly connection) until the calling in of these druid advisers and the arrival of Merlin.

Whatever the origins may have been for this tale, it is now firmly embedded in our folklore, and it remains a wonderful and strange tale, attached to an ancient and magical place.