Former Lewis Merthyr Colliery Bertie winding engine house

The former Lewis Merthyr Colliery Bertie winding engine house is a Grade II* listed building. It features a south elevation made of snecked rockfaced sandstone, while the longer east and west side elevations are constructed from rubble sandstone with rockfaced stone dressings, and the north elevation is made of red brick. The building has a Welsh slate roof and is a single-storey rectangular gabled structure with five bays on the sides and three bays on the gable ends.

The south elevation showcases tall pilasters on either side of a central round arched doorway, which contains a six-panelled double door and a radially glazed fanlight. This doorway is flanked by two long multipane windows that have been renewed. The elevation also features quoins and a plinth. The east and west side elevations have round arched windows with renewed multipane glazing, complete with rockfaced voussoirs, keystones, quoins, and sills. The north gable has four round-headed windows that provide a view of the headframe, along with a pair of winding cable slots at the center. This gable was originally timber with a different pattern of fenestration but was partly rebuilt in brick in the early 20th century, while the sides remain rockfaced stone. The stone bases of the headframe supports are attached at the corners, and the roof includes two ventilators.

Inside, the building is open to a timber-framed roof, with brick pilasters along the sides. The interior is painted black, and an electric motor that powers the large winding drum occupies the northern floor area, while the rest of the space is used for audio-visual presentations.