Building 1, former Elsecar Ironworks casting shed

The former casting shed of the Elsecar Ironworks, built in the 1850s, was later used as a locomotive shed. Constructed from brick, the southern gable incorporates the earlier stone boundary wall of the ironworks. The building features modern sheet metal roofs.

Originally, the shed was thought to consist of two large spaces divided by a central transverse wall, with access through wide archways in the side walls. It has since been converted into a single, undivided space, accessible through the northern gable, with an inserted upper floor and store rooms at the southern end.

On the exterior, the western elevation, which is the original front, has three broad arched openings. The southern two openings have been infilled, while the northern opening is now internal to a mid-20th century lean-to extension that has four bays and large segmentally-headed iron-framed windows. The eastern elevation has undergone extensive alterations but originally featured a series of tall, round arched windows, which are now blocked. At the southern end, there is a wide arched opening, similar to those on the west elevation, which is also blocked and may represent an early alteration. Both gable ends have three original semi-circular openings set high in the gables, now blocked. The north gable contains two locomotive entrances, with the eastern entrance now being internal to the northern extension.

Inside, the walls show evidence of former working arrangements, including various alcoves and iron fitments. The blocked former openings are also visible. The roof structure features timber king-post trusses.