A three celled L-shaped quarry building within Bryn-mawr quarry (NPRN 400669). It is constructed of rounded stone foundations on the north side and a quarried stone and slate superstructure. The walls are of double thickness and the overall dimensions of the site are 12m long by 8m wide with walls surviving up to 2m high on the downslope side. The site is marked on the OS 1st Edition mapping. P.J. Schofield, OANorth, 13th June 2007