St Cynog's Church in Defynnog contains an ancient stone with Ogham inscriptions. Though most of the attractive building we see today is 15th century, the origins of St Cynog's go back to at least the Norman period if not earlier. There is 11th century stonework in the north vestry wall, and the font and holy water stoup may be 11th century or possibly even pre-Norman. The richly carved font is inscribed with Runic letters, the only example in Wales of a Runic inscription.
The churchyard contains several yew trees, of which the largest has a girth large enough for it to be 1300–3000 years old. An adjacent yew was reported in 2014 to be genetically identical to the largest, leading to conjecture in the popular press that the two trees were remnants of a single 5000-year-old tree; but this conjecture has been disputed on the grounds that layering is a more plausible origin for the adjacent tree. The crown of the largest tree is 60 ft in diameter.
References:La Hougue Bie is a Neolithic ritual site which was in use around 3500 BC. Hougue is a Jèrriais/Norman language word meaning a \'mound\' and comes from the Old Norse word haugr. The site consists of 18.6m long passage chamber covered by a 12.2m high mound. The site was first excavated in 1925 by the Société Jersiaise. Fragments of twenty vase supports were found along with the scattered remains of at least eight individuals. Gravegoods, mostly pottery, were also present. At some time in the past, the site had evidently been entered and ransacked.
In Western Europe, it is one of the largest and best preserved passage graves and the most impressive and best preserved monument of Armorican Passage Grave group. Although they are termed \'passage graves\', they were ceremonial sites, whose function was more similar to churches or cathedrals, where burials were incidental.