David M. Rubenstein, President of The Economic Club of Washington, D.C. (Jeffrey MacMillan)

A $5.4 million donation from David M. Rubenstein, co-founder and co-chief executive of D.C.-based private-equity firm The Carlyle Group, and a philanthropist known for contributions to landmarks of American history, has completed fundraising for the renovation of the Smithsonian’s Renwick Gallery.

The building, the Smithsonian’s third oldest, houses craft objects and decorative arts from the 19th century to the present, and the donation is the final part of a two year, $30 million public/private campaign to overhaul infrastructure and renovate the Grand Salon, which will be named in honor of Rubenstein.

The building is currently closed. Construction, which began in early 2014, is expected to be completed within 18 months.

Monday’s announcement came after the Smithsonian's Board of Regents meeting, which also included the announcement that the LeRoy Neiman Foundation has given $2.5 million to the National Museum of American History, to support the Jazz Appreciation Month endowment and upgrade the first floor cafe, which will be named in Neiman’s honor.

The secretary of the Smithsonian, G. Wayne Clough, also announced that the National Museum of African American History and Culture, which broke ground in February 2012 on a five-acre site adjacent to the Washington Monument, will open in the spring of 2016 instead of the late fall of 2015 as had been scheduled. Problems with the water table were discovered after excavating the site, which then had to undergo a re-engineering, which also added about $20 million to the $500 million project.

Fundraising for the project has gained momentum in the past year-and-a-half, Clough says, with private fundraising, expected to be about half the total cost, at about $170 million. “I think they’ve got the momentum they need to finish it off,” Clough said.