"One of a series of disused iron ore mines in the hills north-east of Castell Coch, Tongwynlais, now lying within Fforest Fawr Country Park. A substantial opencast pit provides access to a passage descending steeply for about 50m. It has long been abandoned and presumably dates to the nineteenth century, although there are claims that it was worked in the sixteenth century, or even earlier. The triple entrance has give rise to the popular name of 'Three Bears Cave' and it has been frequently used as a natural set in various TV productions."
Paul R. Davis, 2016.