# Rerigonium (literally 'very royal place'), is already shown on Ptolemy's map of the world. This #dun or royal court of the #Celtic #Novantae tribe is a strong contender for the site of Pen Rhionydd, referred to in the Welsh Triads as one of the 'three thrones of Britain' associated with the legendary #KingArthur, and may also have been the caput of the sub-Roman #Brythonic kingdom of #Rheged. #Rerigonium's exact position is uncertain except that it was 'on #LochRyan', close to modern day #Stranraer.
Source: https://en.wikipedia.org/wiki/Galloway#Galloway_landmarks_on_Ptolemy's_map