Caer-gynydd Colliery is located in the shallow valley of the Gors-fawr brook which lies to the immediate south of Waunarlwydd, on the neck of the Gower peninsula. A nineteenth-century mine, it was still in use at the time of the first-edition Ordnance Survey map of 1879 but had gone out of use by 1899 when the second edition was published. Newspaper reports suggest that it briefly came back into use in the early years of the twentieth century (in The Cambrian a share sale was reported in 1900, a strike in 1902), before the company was wound up by order of the Swansea Court in 1904 (Weekly Mail 02.07.1904). Re-starting prospects were considered in 1904 when the colliery was put up for sale but this was followed by requests to 'fence in the colliery as it was a danger to the public' (The Cambrian 23.09.1904; 23.03.1906). The company was finally struck off the list of joint stock companies and dissolved in 1910, followed by confirmation by H.M.Inspector of Mines that 'the Caergynydd Old Pit had been fenced up' (The Cambrian 12.02.1910; 05.08.1904;12.08.1910).

A ventilation shaft was the most prominent surviving feature of the site (NPRN 422032) until it was demolished in April 2017.

Other sources:
OS County Series 25-inch map sheet: Glamorgan XXIII.3 (editions of 1879, 1899 & 1940)

David Leighton, RCAHMW, 3 May 2017