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.

The cast house was built 1788-9 with the first furnaces. It was demolished in the late C19 when a hot blast stove was built.

Former cast house 20m square. Only part of the S wall is now visible: footings survive set back from the foundry (nprn 67620), while part of the wall further W is incorporated into the rear wall of a later C19 storage shed (nprn 67617).

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