The Smithsonian Institution, accepting a $45 million gift from the Donald W. Reynolds Foundation, announced yesterday that the two museums and other facilities in the Old Patent Office Building would be called the Donald W. Reynolds Center for American Art and Portraiture.

The Las Vegas-based foundation, now the second largest donor in the Smithsonian's history with a total contribution of $75 million, directed its new multimillion-dollar support to the renovation and exhibitions at the landmark building. The National Portrait Gallery and the Smithsonian American Art Museum, which are housed in the building at Ninth and F streets NW, will retain their individual names.

The decision marks the third time the Smithsonian has given major donors the privilege of having their names on a publicly funded national museum, a growing and controversial practice among many museums and performing arts centers that are looking for ways to acknowledge sizable donations in tight economic times.

The Reynolds money will "not only help restore this building to its past glory, but take it to an aesthetic and functional level which will, at long last, allow it to reach its full architectural potential," said Smithsonian Secretary Lawrence M. Small, at an upbeat news conference. "Our progress on this building has taken a great leap forward with this gift."

About $20 million remains to be raised to complete the project, officials estimated yesterday.

The building has been closed to the public since 2000 for a makeover that has escalated in price over the years from $60 million to more than $250 million. The 382,000-square-foot building is being restored to its 19th-century look, with all the floor space devoted to the museums, but with 21st-century accouterments.

In his remarks, Small listed the renovation's highlights, including a conservation center, a 346-seat auditorium, a restored courtyard with a glass canopy over it, designed by architect Norman Foster.

"The complex of specialized and shared facilities . . . all of these activities will be collectively known as the Donald W. Reynolds Center for American Art and Portraiture," Small said.

Fred W. Smith, the foundation's chairman, said that the Smithsonian submitted a proposal during the summer and the trustees decided to react quickly. In 2001 the charitable group came up with $30 million to save the Gilbert Stuart painting of George Washington from the auction block.

This time, Smith said, it wanted to help preserve the building, one of the oldest structures in Washington. "We join the Smithsonian Institution in saving and restoring a significant piece of American history," Smith said.

The work has been financed by $166 million from Congress and the remainder raised privately. Over the course of five years, the rising costs of materials, delays to the canopy project and the request from the National Capital Planning Commission to rebuild a set of stairs on the F Street side have increased the cost of the project. Sheila Burke, the deputy secretary and chief operating office, said yesterday "the final amount is not yet known," and probably $20 million was left to raise. The Reynolds gift, she added, "doesn't close the gap."

While the Reynolds gift will be acknowledged on the exterior of the building, the Smithsonian has already designated other donor spaces. The conservation laboratory will be called the Lunder Conservation Center after the foundation that has given $5.7 million; the auditorium will be named after Nan Tucker McEvoy, who donated $11.6 million; the courtyard, for Robert and Arlene Kogod, who contributed $25.5 million, and the open storage facility for the Henry Luce Foundation, which gave $12.3 million.

Marc Pachter, the portrait gallery director, said the Reynolds gift didn't have any restrictions. "How to spend it, that was left for us to decide," he said.

The largest donor to date at the Smithsonian is Kenneth E. Behring, a Californian businessman, who donated $100 million to the National Museum of American History and the National Museum of Natural History. At Natural History, the Behring family name is attached to the rotunda and the mammals hall. The Behring Center has been added to American History's name. The addition to the National Air and Space Museum at Dulles International Airport is named the Steven F. Udvar-Hazy Center after its businessman benefactor, who has given a total of $66 million.

The two art museums at the Old Patent Office Building have 60,000 works and 550 windows. Yesterday, Elizabeth Broun, the American Art director, and Pachter outlined the initial exhibitions for the opening in July 2006.

American Art will mount five shows, including surveys of William Wegman, William H. Johnson and William Christenberry. It will also have an exhibition on childhood in the 19th century and a history of the building. The portrait gallery will have 11 installations, including one on Walt Whitman, who worked as a nurse in the building when it served as a hospital during the Civil War, and another on images of U.S. presidents.

The Reynolds foundation was started in 1954 by Donald Reynolds, the owner of a chain of newspapers and other media businesses.

The Reynolds Foundation's $45 million donation will help finish renovations to the National Portrait Gallery and American Art Museum, above.