The Cantiorix Inscription is a stone grave marker of the early post-Roman era found near Ffestiniog in north Wales and now at the church at Penmachno. It is notable both as the first known historical reference to the Kingdom of Gwynedd, and for its use of the Roman terms for 'citizen' and 'magistrate'.
It is considered by some to be evidence that a Roman-style administration existed beyond the Roman departure from Britain in some form in the early Kingdom of Gwynedd, while others either question or discount its significance in that regard.
John Rhys had read the Latin text as "Cantiori Hic Jacit Venedotis Cive Fuit Consobrino Magli Magistrati" in his Lectures on Welsh Philology (1877), noting that "the person commemorated was a man of importance, and a Venedotian citizen, whatever that may exactly mean".Thomas Charles-Edwards was more precise in After Rome (2003), noting technical details such as an all-capitals text and the use of late spoken Latin (e.g., CIVE instead of the formally correct CIVIS) to date the inscription to the fifth or sixth century, and neither before nor after that. He translated the inscription as "Cantiori lies here; he was a citizen of Gwynedd, a cousin of Maglus the magistrate", adding his broader thesis that "As well as the language, the political discourse of the Empire survived".
The Cantiorix stone was found near Ffestiniog at the site traditionally known as the 'Graves of the Men of Ardudwy' (Welsh: Beddau Gwŷr Ardudwy). The site has been destroyed over time, with little but the Roman road now visible. Antiquarian accounts include references to "likely long-cist graves marked by upright stones, suggesting a cemetery, as well as cairns, stones and other remains, which are thought to have included burial monuments of prehistoric date."
The importance of the reference to early medieval Gwynedd is uncontested, but the implications of the inscription's use of the terms 'civis' and 'magistrate' is varied. Rhys expressed doubt as to the inscription's meaning of 'civis', while Charles-Edwards suggested that it was evidence of a Roman-style "political discourse" in early medieval northern Wales.