Almost all of the steel industry has vanished from the Pittsburgh area, once home to the heaviest concentration of blast furnaces and other such mills in America. Two of the Carrie Furnace's seven blast furnaces still stand, last used in 1978, monuments to the Industrial Age. A non-profit organization gives tours of the site. Just beyond the furnaces, the prototypical Rust Belt city of Rankin retains much of its 19th-century architecture, including numerous churches.