Two limekilns were built into the hillside of Twyn-y-ffald at Penwyllt. They were constructed of roughly coursed rubble and although largely collapsed their internal access chamber is intact. The northern kiln was probably built by John Christie in 1822-23 whilst the southerly one was erected later. Both kilns were leased by the Brecon Forest Tramroad Company in 1828 and one was enlarged by the company in 1836. Short tramroad branches led from the Brecon Forest Tramroad (nprn 406399) main line to the charging-bank and to the kiln-mouth, the latter passing through a 'lime shed' (nprn 80194) near Patti Row.
RCAHMW, 10 February 2009.