Llys-y-Gwynt was an eighteenth-century cottage which stood to the south of the modern Llys-y-Gwynt Services and to the north of the present Llys-y-Gwynt house and Carneff Howel cairn (NPRN 302739). It was had chamfered timbers and a croglofft with a lathe and plaster partition. The ground-floor was unpartitioned. The cottage was described as being in a good condition in the 1950s but has since been demolished.

(Sources: 1st, 2nd, 3rd, and modern edition O.S. Maps, RCAHMW, An Inventory of the Ancient Monuments in Caernarvonshire (London: Her Majesty's Stationery Office, 1956?1964), vol I, p. 332 and vol. 3, p. clxxiv).
A.N. Coward, RCAHMW, 05.11.2018