The ironworks at Blaenavon lie in the north-eastern corner of the South Wales coalfield and were largely responsible for the development of both the iron and coal industry in this part of Wales. Blaenavon Ironworks today represent one of the most important monuments to have survived from the early part of the industrial revolution. The history of the ironworks comprises two main periods, the iron producing era and the steel-producing era.
Blaenavon Ironworks were built on land leased from Lord Abergavenny in 1787 by three partners, Thomas Hill, Benjamin Pratt and Isaac Pratt, and by 1789 the three original blast furnaces had been constructed at a cost of £40,000. To ensure efficiency the contours of the land played an important part in construction. A hill slope was cut back to form a sheer cliff and the brick and stone furnaces were built abutting it. This meant that the ore, coke fuel, and limestone required in the iron-making process could be introduced into the furnace from the high ground immediately above. As the material travelled down the interior of the furnace, the heat within would be intensified by 'blasts' of air provided by a steam engine. Once molten, the material would be tapped off into sand moulds that had been made on the floor of the casting house built immediately in front of the furnace.
Although Blaenavon Ironworks may appear largely derelict, the robbing of some stone now allows the structures in the complex to be seen almost as a cross-section. As you stand from the viewing area near the cottages of Stack Square, the two casting houses with arched openings and gabled roofs can be clearly seen to the left of the site. The furnaces that stood behind these casting houses have now largely gone. However, the later number four and five furnaces to the right of the site, built c1810, are exposed as the casting houses in front were demolished in 1880. Although these two furnaces were robbed of much of their outer stone casing in 1911 to provide building materials for a new church, this action now gives the visitor the opportunity to view the exposed inverted 'bottle-shaped' firebrick lining.
At the top of the cliff are the remains of the Calcining Kilns that were used to prepare the raw materials. Coal would be turned into coke, and the iron ore would be roasted to remove certain impurities. The dominant structure to the far right of the site is a water balance tower, effectively a water driven lift, which was built by the engineer James Ashwell in 1839. The lift was designed to facilitate the movement of materials and finished iron, from the yard, to the higher ground. The houses in Stack Square, recently restored, were built between 1789 and 1792, probably for key workers. The taller building at the south-eastern corner was once the company shop.
In 1880 the workings at Blaenavon had taken second place to a new foundry across the valley that also boasted two Bessemer Converters for steel production. The number two furnace at Blaenavon was retained to produce cold blast pig iron, whilst the newer number four and five furnaces were converted to produce iron ingots for the steelworks. As mentioned previously the casting houses were removed from in front of these furnaces to allow rail tracks to be laid directly up to the tapping area. Trucks carrying ingot moulds would be brought up so that the molten iron could be ladled directly in. The trucks would then be transported across the valley on a viaduct to the new steelworks.
The Blaenavon site continued in operation until the turn of the century, but finally shut down iron production in 1904. Although seeing a brief resurgence of activity during both world wars producing shell steel, Blaenavon Ironworks functioned for the bulk of the 20th century largely as a coal yard and workshops, finally shutting down completely in the 1960s. Destined for complete demolition and in a dangerous state of repair the works were saved by Blaenavon Urban District Council who presented the site to the Ministry of Works and Ancient Monuments (now Cadw) to be preserved for the nation.