WASHINGTON – The irony of the father of the Bill of Rights owning slaves is not lost on philanthropist David Rubenstein, who announced this weekend that he is giving $10 million to Montpelier, the historic Virginia home of the nation's fourth president, James Madison.

The Montpelier gift, announced at the site, will fund reconstruction, refurnishing and archaeology at the plantation that Madison's family occupied with its slaves for several generations. Madison served as president from 1809 to 1817. When he retired, he moved with his wife, Dolley, back to the plantation where he had grown up and where his mother still lived.

Rubenstein wants to help make the estate more authentic. Montpelier could draw more visitors to learn about history, he said, if the house is fully restored and its slave quarters built out. It currently draws about 125,000 visitors a year. Last year, Rubenstein gave money to recreate slave quarters on Thomas Jefferson's plantation.

"It's this dichotomy. You have people who were extraordinarily intelligent, well-informed, educated; they created this incredible country — Jefferson, Washington, Madison — yet they lived with this system of slavery. Jefferson, Washington and Madison all abhorred slavery, but they didn't do, they couldn't do, much about it," he said. "We shouldn't deify our Founding Fathers without recognizing that they did participate in a system that had its terrible flaws."

Rubenstein — who is the billionaire co-founder of the Carlyle Group, a global private equity firm — has a passion for U.S. history. He said he called Montpelier several months ago and asked whether he could visit. "I came down and looked around," he said, and was struck by the story of Madison's diligence, learning and behind-the-scenes work ethic.

"He devoted himself entirely to public service," Rubenstein said. "He got things done."

The gift is an "amazing and pivotal moment," said Kat Imhoff, president of the Montpelier Foundation, which operates the site and is receiving the donation.

The Madisons lived in the house for much of their lives, and Madison died there June 28, 1836, at age 85. Both are buried on the property.

Madison, who could read Greek, Latin, Spanish, Italian, French and Hebrew, did much of his political thinking in Montpelier's libraries, which held 4,000 books. The mansion was substantially altered after it passed from Madison's family but was restored to its 1817 appearance during a multiyear project that ended in 2008, Imhoff said.

But many rooms haven't been refurnished because historians aren't sure how they looked in the early 1800s. About $6.5 million of Rubenstein's gift is going toward research and refurnishing those rooms.

About $3.5 million will go to archaeological and other work on a small complex of slave cabins, a kitchen and two smokehouses that stood just south of the mansion. Experts believe about 30 people — "house slaves" and their families — occupied what were relatively comfortable structures. The plan is to reconstruct the buildings and furnish the complex. The plantation's "field slaves" lived in more spartan cabins of logs and mud near where they worked, said Montpelier's director of archaeology, Matthew Reeves.

Madison, although troubled by slavery, at one point owned 118 slaves. It is said he talked more on the subject of slavery than on any other.

The Associated Press and Washington Post contributed to this report.