This former concrete-block building is part of a small 20th century colliery, NPRN 528730, on the western side of Merthyr Common. It is on a terrace revetted into the slope and measures 4.5 metres north northeast to south southwest by 3 metres, and the walls still stand up to 1.25 metres high. About 1 metre to the west of the building there is a low concrete- block wall that runs along the western side of the terrace. In the southern wall was two small circular holes, presumably for pipe work. When the area was surveyed as part of the Uplands Initiative by Trysor in 2012 vegetation cover was grass and nettles. J.J. Hall, Trysor 25th January 2013
