The vacant Carrie Furnaces, a relic of the industrial age that gave Pittsburgh its identity, has been designated a national historical landmark by the National Park Service.

Today, U.S. Congressman Mike Doyle, D-Swissvale, will announce that Carrie Furnaces 6 and 7, which once produced iron for the U.S. Steel Homestead Works, has joined the ranks of about 3,000 national historic landmarks throughout the country.

August R. Carlino, president and chief executive officer of Rivers of Steel National Heritage Area, said the announcement is the culmination of an application process that began 16 years ago and has been endorsed, and supported, by a host of public officials.

"It is sentimental, thinking about it," Mr. Carlino said yesterday. "This is the culmination of all the men and women who worked in that mill over the decades. Everything they did made that site supremely significant in the history of the nation."

The designation doesn't bring any direct money to the furnaces, which may cost between $75 million and $100 million to restore. But the designation gives the mill historical protection and makes it a candidate for funds that are available to preserve and restore national historic landmarks.

"It is the highest level of historic recognition that the federal government offers," said Bill Bolger, national historic landmark program manager in Philadelphia. He said the job of bringing money to the sites depends on the efforts of local advocates.

Public officials from across the Monongahela Valley have been invited to an event at 2:30 p.m. today at the Pump House at the Waterfront, where Mr. Doyle will make the announcement.

Carrie Furnaces 6 and 7 in Rankin are rare examples of pre-World War II iron-making technology. They opened in 1884 and were acquired by Andrew Carnegie in 1898 as a source of molten iron for his steelmaking furnaces across the river in Homestead.

For years, Mr. Carlino's organization has been spearheading efforts to integrate the old mill into a 38-acre national park site that would span both sides of the Monongahela River and be linked by an old hot metal bridge.

The park would focus on the region's iron- and steel-making and on the events surrounding the 1892 labor lockout and fight between steelworkers and Pinkerton guards, which was one of the bloodiest labor disputes in U.S. history.

The park would be linked by a hot metal bridge that once carried pig iron from the Carrie Furnaces to Homestead.

Mr. Carlino said legislation moving through Congress would let the park be created.