From around 550 AD onwards a number of Celtic Saints arrived in Britain, many from what is now Brittany in France.
One of the most important of these Saints was Illtyd, who established a church and teaching college at LLantwit Major. This could well have been the first university in Britain. It was certainly the most important centre of learning for many years.
The Welsh name for LLantwit Major is LLanilltyd Fawr, which means the church of the great Illtyd.
Illtyd had a very significant impact of the early Celtic Church and as well as teaching and mentoring many other holy men and women who were later recognised as saints themselves, such as Saint Patrick, Saint David, Saint Samson (associated with Caldy Island) and Gildas the historian.
Illtyd is sometime referred to as Illtyd Farchod, that is, he rode a horse and was a knight. Somewhat unreliable sources in the 1100s refer to him as King Arthur’s cousin.
The church at Llangan is dedicated to St. Canna who was reputedly the sister-in-law of Saint Illtud. Saint Canna was a princess from Brittany who first settled around what is now Cardiff, giving her name to Pontcanna and Canton (Treganna in Welsh).
The Celtic Wheel Cross at Llangan is of the 9th or 10th century. Located near the west wall of the church is a disc-headed cross slab, 1.3m high, depicting the crucifixion, set now in a shelter to prevent further erosion from the weather.
Just below the Church at LLangan there is an area of boggy ground, around 10m from the stone wall that encloses the burial ground. This could be a former Holy Well or spring associated with Saint Canna.
Saint Canna later moved to Carmarthenshire where there is another Church and Holy Well named after her.
Canna was also supposedly the mother of St Crallo, who established a church at Coychurch (LLangrallo in Welsh).
The present day church is a Grade 1 Listed Building.