Carnegie Steel Company was a large steel manufacturer primarily founded by industrialist Andrew Carnegie (1835-1919) in 1892, headquartered in Pittsburgh, Pennsylvania. Andrew Carnegie began working in the iron and steel industry years earlier. In 1865, he left his superintendent position at the Pennsylvania Railroad to form the Keystone Bridge Works. Carnegie built two blast furnaces next to the Keystone Bridge Works called the Lucy Furnaces, named after his brother, Thomas Carnegie's (1843-1866) wife, Lucy Ackerman Coleman Carnegie (1847-1916). Lucy Furnace No. 1 was built from 1871 to 1872; Lucy Furnace No. 2 started operation in 1877. After learning the Bessemer steel process, the plant switched from iron to steel.

Throughout the 1870s and 1880s, Andrew Carnegie founded several ironworks and steelworks, and business partner Henry Frick (1849-1919) suggested that he consolidate all the plants under one company. The consolidation formed the Carnegie Steel Company. The Lucy Furnaces ceased operation in 1930 and were demolished in 1937.