The Carrie Blast Furnaces, built in 1881 as part of Pittsburgh's Homestead Steel Works, were once among the world's most productive iron producers. Furnaces 6 and 7 operated until 1978, producing up to 1,250 tons of iron daily. After the plant's closure in 1982, the site sat largely abandoned until 1988, when the Park Corporation acquired it. In 2005, Allegheny County purchased the land, and in 2006, the remaining furnaces were designated a National Historic Landmark. Rivers of Steel Heritage Co