Blaenavon Ironworks began production in 1789 with 3 furnaces. Two more furnaces were built c1810. The original partnership, led by the Hill family, sold the works in 1836 to the Blaenavon Iron and Coal Co. Initial investment at the site included the construction of a water balance lift for conveyance of pig iron from the site, but further investment did not occur until the 1850s. A new blast engine was built, and a new furnace was blown in during 1861. Investment was also made on a new site kown as Forgeside. By 1900 only one furnace remained in blast, but this was blown out in 1904. Thereafter the site was used by small-scale engineering companies until it became a guardianship monument in 1974.

Furnace 6 was blown-in during 1861 and is of the contemporary type with a round stack strengthened by iron straps.

Round blast furnace of coursed rubble stone with iron straps. It survives up to 5m high. On the E side a tuyere recess has an arch framed by cast iron, just visible above uncleared rubble. The W side has a similar arch to the splayed recess. The rear was inaccessible.

R Hayman, Hayman & Horton, 6/1/2003