The Lincoln Memorial, seen Feb. 12, will be repaired and refurbished with the help of a gift from David Rubenstein, who is giving $18.5 million to the National Park Service for the work. (Evelyn Hockstein/For The Washington Post)

The National Park Service announced Monday that the Lincoln Memorial will undergo a major renovation over the next four years, thanks largely to an $18.5 million donation by billionaire philanthropist David Rubenstein.

The project is probably the biggest overhaul of the building since the structure was dedicated in 1922, officials said.

The memorial, which attracts 7 million visitors a year, will remain open during the work, although parts of it may be closed off from time to time.

The marble-columned edifice, which houses the 120-ton statue of a seated and contemplative Abraham Lincoln, is one of the most elegant and hallowed memorials in the ­country.

Much of the work on it will take place inside, beneath the massive chamber that holds the statue.

The limited exhibit space will be greatly expanded, along with the memorial’s tiny bookstore and antiquated restrooms. New exhibits will be added, and visitors will be able to see the massive pilings and foundation that support the memorial.

Visitors will also be able to see some of the old graffiti apparently left by construction workers who drew caricatures in charcoal on some of the pilings.

The exhibit area, now about 750 square feet, will be expanded to 15,000 square feet, said Sean Kennealy, chief of professional services for the National Mall and Memorial Parks.

The memorial will be scrubbed inside and out. Its crumbling slate roof, which is not the original but has leaked water and stained interior walls, will be repaired.

And its two dramatic 60-foot-long murals inside will be restored.

Damage to some inside brickwork that occurred during the 2011 earthquake also will be repaired.

The formal announcement was made as dignitaries gathered in the snow under umbrellas on the steps of the memorial.

“I assure you I have malice towards nobody for the weather,” Rubenstein joked, using words from Lincoln’s famous second inaugural address. “But charity towards all of you for coming.”

“I’m very honored as an American to be able to contribute in this way,” he said of his gift.

“This is an extraordinary country that enables people from all races, all backgrounds, all ethnicities to be able to rise up and do things that they maybe couldn’t have done in any other country,” he said.

In an interview last week, he said, “The idea was to take the basic Lincoln Memorial and reshape it a bit, make it more modern, scrub it up a bit.”

“When you go to the Lincoln Memorial today, you see this great statue of Lincoln,” he said. “But there’s no real museum or education center about Lincoln. So I think it would be a good idea to have such a thing.”

His gift is the latest in a series of multimillion-dollar donations he has made to historically themed projects around the Washington area.

Last April, he announced a $5.37 million donation to refurbish the U.S. Marine Corps War Memorial near Arlington National Cemetery.

In 2014, he gave $10 million to Montpelier, the historic Orange, Va., home of James Madison; $5 million to the White House Visitor Center; and $12.3 million to Arlington House, the home of Robert E. Lee.

And after the earthquake, he paid $7.5 million of the $15 million cost to repair the Washington Monument.

Rubenstein is a co-founder of the Carlyle Group, a Washington-based global private equity firm.

Gay Vietzke, superintendent of the National Mall and Memorial Parks, said the goal is to broaden the story of Lincoln.

“This place has become symbolic of so much more,” she said last week. “And in this tiny footprint, it’s near impossible to talk about . . . the power of the place and Lincoln’s legacy and why it’s really relevant to us today.”

“Our hope is we’re going to do that with this very, very special gift,” she said.

The money will go to the National Park Service through the National Park Foundation, the Park Service’s nonprofit fundraiser, officials said. The Park Service will kick in about $6 million to the project.

“This is a very long overdue rehabilitation,” said Will Shafroth, president of the National Park Foundation. “It’s old and tired.

“In some ways, we’ve let this place get . . . run-down,” he said. “The improvements that are going to be made are going to make it a much more welcome place to be.”

The Park Service is celebrating its 100th anniversary this year and is in the midst of an effort to raise $350 million in donations, Director Jonathan B. Jarvis said. It has a nearly $12 billion backlog in deferred maintenance, he said.

The Park Service was established under President Woodrow Wilson on Aug. 25, 1916.

The 38,000-ton Lincoln Memorial is built on fill dredged from the Potomac River. It is supported by a series of huge concrete pilings that were sunk 44 to 65 feet through the fill down to bedrock.

“It’s very cool,” Jarvis said last week. “When we build the new exhibit and visitor-use space, it will . . . give the public an opportunity to actually see underneath the memorial.”

After the announcement Monday, Park Service officials conducted a tour of the cavernous basement, or “undercroft,” of the memorial.

Resembling a dim, subterranean cathedral, the area is filled with the gigantic concrete pilings and arched supports that hold up the structure.

Ground was broken for the memorial on Lincoln’s birthday — Feb. 12 — in 1914. The cornerstone was set a year later. The memorial was dedicated in the presence of Lincoln’s 78-year-old son, Robert, on May 30, 1922.

Jarvis said some of the work will begin this year.

“I feel great about it,” he said.

“It’s our centennial year,” he said. “We’re announcing the restoration of one of our most iconic sites . . . [and] the public phase of the [fundraising] campaign. . . . I’m feeling like it’s a pretty good year.”