Major Steelworks complex built by Tube Investments Ltd. Transferred to British Steel Corporation in 1967. Now privatised. Site originally comprised 2 75 ton 'Kaldo' oxygen steel making units, a 75 ton Electric Arc Furnace, and a bloom, slab, and billet mill. Thrybergh bar mill added 1973 on east bank of the Don (Separate Polygon) (Munford 2003, 88). Previously this site was occupied by piecemeal enclosures to the north of the medieval hall site of Aldwarke. Ornamental planting shown on the 1853 OS.