Mine offices at Llywernog Mine

The mine office building at Llywernog Mine is a two-storey structure built from coursed squared local sandstone, featuring yellow brick dressings and a hipped slate roof. It has a small yellow brick chimney at the right end. The front of the building consists of seven bays, with brick quoins. The five central bays are closely spaced and contain 16-pane windows above three wide doors, which alternate with two similar windows. The windows are designed with small panes in fixed or tilting lights, slate sills, and yellow brick cambered-headed surrounds with rusticated jambs. The doors are made of board and are set in similar surrounds, with the right door designed as a stable door. The right bay features a broader 16-pane window above a square 20-pane window, while the left side has a taller doorway topped with a small brick-framed blank roundel.

On the left end, the building adjoins the wheel-pit for a 50-foot (15.25 meters) wheel, which is listed with the crusher-house. The right end wall has a raised chimney breast. The rear of the building is built into the slope and includes two first-floor doorways and a small roundel to the right. The roof has three 20th-century skylights.

The interior has been restored and is now used as a museum, featuring a smith's hearth at the eastern end.