An early nineteenth-century limestone quarry, started on a large scale in the early 1820s probably by the engineer Joseph Jones of Ystradgynlais, it was connected to the Brecon Forest Tramroad (nprn 406399) and later to the Neath and Brecon Railway (nprn 401414). It was probably used to provide limestone for flux in the upper Swansea Valley Ironworks at Ynysgedwyn (nprn 34037) and possibly at Ystalyfera (nprn 34126). Penwyllt Quarry Railway Upper Section (nprn 80444) transported limestone to two later nineteenth century limekilns (nprn 80443) (probably dating from the opening of the Neath & Brecon Railway in the 1860s) and thence the Penwyllt Quarry Railway Lower Section (nprn 80445) carried burnt lime to a loading platform on a siding from the Neath & Brecon Railway.
RCAHMW, 10 February 2009.