Iron and steel were Pittsburgh's main industries for nearly a century and a half. The mills churned out their products 24 hours a day, 365 days a year. It can be said that steel from Pittsburgh's mills practically built America. From the Empire State Building to the Golden Gate Bridge, steel made in our city found its way into all corners of the developing nation.

The Edgar Thompson Works in Braddock were one of the many steel firms in operation along the Monongahela River.

The Carnegie Steel Homestead Works were the largest steel plant in the United States. The mills were sold by Andrew Carnegie to United States Steel. The mills operated until the 1970s, when the steel industry suffered irreversible setbacks. The land once occupied by the Homestead Works is now home to the Waterfront, a residential and commercial development.