It was built just after the turn of the century in the grand style of Italian Renaissance Revival architecture, a clubhouse for the city's male elite. And then it fell into the hands of radicals, serving as the base of operations for the legendary John L. Lewis and the United Mine Workers of America.

Now the six story building at 900 15th St. NW that once housed the University Club is back in the hands of the elite where it will begin a third life as a luxury apartment building for affluent city dwellers.

Summit Properties Inc., a national apartment developer, this week acquired the mine workers headquarters building for $8 million with plans to redevelop the 88-year-old structure and an adjacent parking lot into 90 luxury rental units. The project will be the latest addition to a small but growing number of residences in a downtown dominated by commercial office buildings.

"There's a tremendous opportunity that exists in the District," said Tom Baum, vice president for development at Summit, a Charlotte company that already owns more than 2,000 apartment units in the Washington suburbs. "We think D.C. is on the upswing and getting better. It's really just now that it's becoming a viable activity to put housing there."

There will be a restaurant and other retail establishments on the lower floors, and apartments upstairs and in a 14-story addition planned for the adjacent parking lot. Occupants won't have many neighbors -- the White House, two blocks away, is just about the closest residence.

The miners are not the only union turning their valuable D.C. property into cash. The United Brotherhood of Carpenters and Joiners of America hopes to break ground this year for a big office building on land it owns at 101 Constitution Ave. NW. In recent years, a number of other unions have sold their downtown headquarters properties and relocated in cheaper quarters.

The grand and the grimy mix at the Mine Workers building, which has been nominated to the National Register of Historic Places. It opened on New Year's Eve 1911 as the University Club, a men's retreat whose stated purpose was "to promote science, literature and art and to provide a club house to promote social intercourse and mutual improvement," according to a history compiled as part of the National Register nomination.

Designed by George Oakley Totten, a local architect best known for the many elaborate mansions he designed along 16th Street and Massachusetts Avenue NW, the building is a reminder of a much grander era for the then-sleepy capital city. The lobby is dominated by a wide marble staircase. On the second floor, elaborately decorated vaulted ceilings soar to 21 feet.

Although built for an elite city leadership, the building today is full of reminders that its occupants represent what once was one of the nation's most downtrodden work forces. Poster-sized photographs of men and boys with coal-blackened faces hang along the halls. An oversize bust of Lewis, who led the miners from 1920 to 1960, glares down from the grand staircase.

Lewis, who founded the then-radical Congress of Industrial Organizations during the Depression, chose to move his union to the building in 1937 so that the miners would have a headquarters worthy of their growing political power.

The University Club moved a few blocks away, to its current home at 1135 16th St. NW.

That year, the former club building was renovated into what contemporary accounts called "one of the most up-to-date office buildings in the city." A full story was added atop the original five; plumbing, wiring, elevators and heating were updated.

Fittingly, the heating system burned coal -- and it still does. A common fuel at the time, coal burning furnaces now are a rarity. The union headquarters may be the last commercial building in the city to burn coal, although no one is quite sure. "It's union coal," UMWA spokesman Doug Gibson said.

The overhaul 62 years ago was the last time the building was modernized and what was cutting edge in 1937 has long been outdated. That's why the union sold the building, Gibson said.

"We decided to sell because the cost to renovate almost equaled what it was appraised at," he said. "We would have had to use members' dues money to renovate."

The union, which employs about 50 staffers, has not decided where it will relocate its headquarters, although it plans to remain in the Washington area, Gibson said. "It was not an easy decision," he said. "It's been our home."

The building's new owners believe plenty of other people will want to make the building home. The market, Baum said, will be high-level workers at large nearby operations, such as the World Bank and the Treasury Department. "It's really dedicated to people who want a live-work environment," he said.

Although the city once set a target of 5,400 new residential units for downtown, only about 2,000 have been built since 1980. Almost all of them are in what's known as the Pennsylvania Quarter, the area that was once controlled by the federal Pennsylvania Avenue Development Corp. A number of other sites in that neighborhood are set to include housing, which could produce hundreds of additional units in the coming years.

In addition to Summit's building, there's one other apartment complex that may be built downtown outside of the Pennsylvania Quarter. That's at 1300 L St. NW, but planning is not far along.

For years developers have resisted building housing downtown, saying that offices were more profitable. According to Baum, the Mine Workers building conversion works financially only because its structure "did not lend itself to development into offices."

But activist Charles Docter, head of Downtown Housing Now, said Summit's plans are an encouraging sign.

"This just proves that housing is coming to downtown," he said. "The city has to keep encouraging it and helping it, but the private sector is realizing that office is not the only thing you can build in downtown."

CAPTION: Opened in 1911, the former University Club -- now the United Mine Workers headquarters -- will be converted into 90 luxury apartments by developer Summit Properties Inc.