A building within the Cwmrhaiadr Mine complex (NPRN 402599), shown on the 1891 Ordnance Survey map, the remains of which were seen when the site was visited in June 2005. It measured 8m x 7m with an additional 5m square terrace adjacent to the building on the north side. Only slight traces of the walls remained, no more than 0.5 m in height. The northern edge had either been heavily robbed or had never been complete. J.J. Hall, Trysor, 23 December 2005