<P> The company headquarters were in the Carnegie Building, an early skyscraper in Downtown Pittsburgh . Built to show its use of steel in its construction, the building was fifteen stories high, and was left uncovered for a full year . The Carnegie Building was demolished in 1952 . It was later rebuilt as a memorial in 2012 . </P> <P> Carnegie made major technological innovations in the 1880s, especially the installation of the open hearth furnace system at Homestead in 1886 . It now became possible to make steel suitable for structural beams and for armor plate for the US Navy, which paid far higher prices for the premium product . In addition, the plant moved increasingly toward the continuous system of production . Carnegie installed vastly improved systems of material - handling, like overhead cranes, hoists, charging machines, and buggies . All of this greatly sped the process of steelmaking, and allowed the production of far vaster quantities of steel . As the mills expanded, the labor force grew rapidly, especially less skilled workers . The more skilled union members reacted with the unsuccessful 1892 Homestead Strike, along with demands for reduced working hours and against pay cuts . After the unsuccessful strike the company continued to expand and profits grew year on year, with the company having earned net profits of $21 million in 1899 . </P> <P> J&L Steel was the most important competitor to the Carnegie Steel Company and U.S. Steel in the vicinity of Pittsburgh . </P> <P> Carnegie Steel Company was sold in 1901 to the United States Steel Corporation; a newly formed organisation, set up by Pierpont Morgan . It sold for $480 million ($14.1 billion in 2016), of which $226 million went to Carnegie himself . U.S. Steel was a conglomerate with subsidiary companies . The name of the subsidiary company was changed to the Carnegie - Illinois Steel Company in 1936 . </P>

Who created the largest steel company in the world