Cefn Cribwr ironworks, the furnace and charging house

The furnace is built of local sandstone, with ashlar arches and quoins. It is 9.75m square on plan, tapering upwards to 6.1m square at the top, originally with a short circular chimney reaching a total height of 10.6m. On each of the four sides are tapered arches, the tapping arch being constructed with very finely laid voussoirs, perhaps later in date, tapering back to the drawing aperture into the tapered square crucible of the furnace. Above this, the furnace is circular and bottle shaped, narrowing to the top. A stone and brick apron paves the area under each arch, with a curved front and a central slot for the main drawing channel leading into the casting house. Foundations exist on the E and W sides. Behind the furnace, a narrow passage is bridged over, with a recess in the retaining wall beneath the charging house. The upper part of the furnace is lost, including the charging level.

The lower storey of the charging house however, survives, comprising one large chamber, now roofless, with an angled opening to the furnace. Behind, two narrower rooms. Openings with splayed reveals, altered in brickwork.