The federal government yesterday placed the once grand Tivoli Theater, an aging and deteriorating reminder of the golden age of movie palaces, on the National Register of Historic Places, but its eventual fate remains uncertain.

The designation, approved by Jerry Rogers, a National Park Service official, does not prohibit demolition, but does make any developer who renovates the facility eligible for a tax credit amounting to 25 percent of the cost of the rehabilitation work.

Nonetheless, Eric Graye, president of Save the Tivoli, a band of about 200 Columbia Heights activists devoted to saving the now-vacant structure at 14th Street and Park Road NW, said the historic place designation "means that it's going to make it more difficult for the city to make a case for tearing it down," as the District government once proposed.

Under a local landmark designation granted two years ago, the city's Historic Preservation Review Board must hold a public hearing before any significant changes can be made to the exterior of the 61-year-old Tivoli.

Several years ago the city gave a group of developers the redevelopment rights to the Tivoli and a nearby parcel. The developers have sought to demolish the theater and replace it with a major shopping complex to serve the 14th Street area that was badly damaged during the 1968 riots.

J. Gerald Lustine, an official of Park Central Associates Corp., said the activists who want to save the Tivoli have "got two choices: You can take what we want or leave it there for another 20 years as it is.

"I just cannot imagine anyone touching that building for economic reasons," he said. "You can't save the whole building."

Lustine said the developers, as an alternative to demolishing the theater, would be willing to save the building's facade 18 feet back into the structure, but not the 2,500-seat theater itself.

In its glory days, the theater offered moviegoers the splendor of plush carpeting, plum damask wall coverings, an enormous ceiling dome with an elaborate chandelier and a $35,000 Wurlitzer organ to accompany silent films