The Carrie Furnaces 6 and 7 still tower 92 feet over the Monongahela River in Homestead, PA. The furnaces are a rare example of steel-making technology from pre-World War 2.
They were built in 1907 and operated until 1978, about the time steel-making declined in the area. At peak production in the 50s and 60s, the ovens put out up to 1, 250 tons of iron a day.
The furnaces, now a national heritage area, have been the backdrop for films including Out of the Furnace, as well as the TV show American Ninja Warrior.