Musgrave engine house and chimney

Musgrave engine house and chimney is a two-storey structure with a hipped roof, featuring a brick passage for the rope drive and a tall brick chimney at its south-west corner. It is built from grey brick made at the copperworks, accented with red brick bands at the cills, lintels, and eaves cornice. The timber roof is slated. Each long side of the building has four tall, square-headed windows with timber frames. The west wall includes a large doorway with remnants of an external staircase, while the east end has an open passage for the rope drive and a high-level doorway. The rope drive extends out of the building to a set of gears and intact rolling mills. The chimney, which is square in section and slightly tapering, is made of brown brick with iron banding near the top.

Inside, the building is lined with red brick and features a main floor that houses the engine, with a service basement below. The engine is one of the first uniflow type steam engines made in Britain, produced by John Musgrave and Sons of Bolton in 1910. It retains its cylinder and piston, valve gear, crank, drive shaft, and flywheel. The uniflow type engine was regarded as the most efficient development of the steam engine, and this is believed to be the only example still existing in Wales.