Foundry at Felin Fawr Slate Works

The Foundry at Felin Fawr Slate Works is a tall rectangular building, oriented roughly north-south. It is constructed from coursed and dressed slate slabs, featuring granite quoins and a gable-ended slate roof with stone kneelers and circular brace plates. On the western side, there are four timber windows, each with three lights, long slate lintels, and cills. The south gable end once had an external, tapering square stack made of orange brick, with the remaining brickwork rising above a round-arched opening; there is an infilled doorway to the right. The north gable end has a similar arch and also includes a small lean-to roofed section in the north-west angle. The eastern roof slope features rooflights, while the wall below is concealed by an adjoining fitting and repair shop. At the southern end, a lower gabled, slated range with a small brick stack runs at right angles to the west, against which is an open three-bay slate-roofed lean-to supported by cast-iron columns; the eastern bay overlaps the southern gable end of the main building.

Inside, the building retains massive wooden trusses with braced timbers on cast-iron brackets, which once supported a travelling crane.