Plas-y-gors is situated 2km north of Ystradfellte, off a minor road into the forest, just north of Nant Plas-y-gors. It is a ruined farmstead, probably 18th-19th century, built of squared rubble in lime mortar, with dressed quoins and jambs to the openings on the front wall. The boundary walls of the farmstead (running westwards from the two ends of the range) were planned, with keying blocks left projecting from the buildings, and no quoins below them. All openings in the front had voussoir arches, all others had flat stone lintel and the roofs were all slate. The house seems to have been of 2.5 storeys in the front, with a lean-to 1.5 storey rear kitchen. This has a deep fireplace and smoking-hole with a flue connecting to the main chimneys, with a cellar below the south room. The position of the stairs is indicated by an extension of the cellar under the 'hall'. The outbuildings are almost featureless. At the north end is a building with a buttress on each lateral wall, which may have been a barn, though not for threshing. At the south end, steps lead to the (now destroyed) first floor of the range, probably either a granary or servants' accommodation. The building below it might be a stable, with a stable beyond it.
(Source: NMR Site files, AJ Parkinson, 22 July1975)
Ian Archer, RCAHMW, 21st February 2005