Former Llanbradach Colliery engine hall

The former Llanbradach Colliery engine hall is a long, single-storey building with a gabled roof, consisting of three parallel sections oriented north-south. The western section is shorter and features a three-bay facade on the north side. The north and west walls are constructed of rubble sandstone with rock-faced dressings, while the east and south walls are made of snecked, rock-faced sandstone. The original roof has been replaced with corrugated metal sheets behind coped gables and raised ridges.

On the north side, the central bay is buttressed and includes an oriel window with iron-frame glazing that is blocked behind the glazing bars. Below this window is an inserted door for vehicle access. The left and right bays each contain three stepped round-headed windows with iron-frame glazing. The left bay has recently added projections below, while the right bay features an inserted doorway and a blocked segmental-headed window.

The east elevation is also buttressed and has two tiers of windows, with the lower level grouped in a pattern of three, four, four, four, and three, and the upper level in a pattern of one, two, two, two, and one. The upper windows have a continuous sill band. The segmental-headed windows retain original iron-frame glazing at the south end, but most have been replaced at the north end due to recent internal divisions. Near the south end, there is an additional buttressed bay with a square window above a former opening for winding cables, which is now blocked.

On the south elevation, the central and east bays feature oriels above a wide inserted doorway, with blocked segmental-headed windows to their right. The west range is set back and has an oriel above an added lean-to.

Internally, the building has been subdivided into one large unit at the north end and two smaller units at the south end. The interior remains open to the roof, supported by wrought iron trusses, with the valleys of the roofs carried on rows of steel uprights. The walls have a dado of brown tiles, above which they are plastered with panelled pilasters and a moulded cornice. The central range retains a travelling crane on wrought iron columns and girders at the north end.