Caer Carreg-y-Fran is an early defensive enclosure situated at 550ft on a small hill overlooking the north end of the Llanberis Pass. Within the defensive enclosure there are remains of six huts, ranging from 15 to 25 ft in diameter. The site is encumbered by modern walls and has been partly disturbed by mining.
Source: Caernarvonshire Inventory, Vol. II, Ref. No. 1314, Fig 150.