Llanfair-is-gaer was an ecclesiastical parish in Caernarfon, Gwynedd: [1] the parish church was St Mary's. [2]
The ancient parish of Llanfair-is-gaer comprised the five townships of Bonyrafallen, Botandreg, Brynffynnon, Llanfair Isaf and Portdinorwig. [3]
53°10′12″N4°14′35″W / 53.170°N 4.243°W