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 retaining wall is contemporary with the building of the works in 1788-9 and was extended E c1810 when Furnaces 4 & 5 were built. It has been modified on several occasions, including the insertion of circular brickopenings leading to integral chambers at high level. These were for the insertion of cast iron pipes recycling heat from the blast furnaces to heat the boilers.

Mainly a rubble stone retaining wall 15-20m high, with returns at either end. The return at the W end retains springers for a former tunnel-vaulted passage beside Furnace 1. Behind the foundry (and behind the site of the original blast engine) the wall has been reconstructed in brick, incorporating a wide but shallow segmental recess, above which is exposed bedrock.. The return on the E side abuts the Balance Tower (nprn 67613) and appears to incorporate stone steps.

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