An Arlington developer has donated $15 million to the Thomas Jefferson Foundation, which owns and operates Monticello, the home of the nation's third president.

"This assures in perpetuity that Jefferson's legacy will be studied and shared with audiences of all ages around the world," Dan Jordan, president of the Charlottesville-based foundation, said of the gift from Robert H. Smith and his wife, Clarice. The money will go mostly to fund and expand the work of the foundation's international center, which has been renamed the Robert H. Smith International Center for Jefferson Studies.

Smith is chairman of Charles E. Smith Commercial Realty and Charles E. Smith Residential.

For a decade, the center has tried to spread throughout the world Jefferson's ideas on democracy and liberty, publishing 23 books, playing host to 18 conferences for scholars and public officials on both sides of the Atlantic and providing more than 100 academics with the chance to study the "Sage of Monticello."

About $1.5 million of the Smiths' gift will be used to expand those programs and to broaden them to include children as well as to do archaeological research on the Monticello plantation. About $1 million will be used to upgrade the center's historic 78-acre campus across from Monticello. It includes the 1940s home Kenwood, which was used as a retreat by President Franklin D. Roosevelt. The remainder of the money will go toward the center's endowment.

The foundation announced the gift, the largest in its 80-plus-year history, at an annual black-tie affair Friday night at Monticello.

"I am a grateful American," Jordan quoted Smith as telling his audience. Jordan described Smith as a believer in the ideals of America's founding fathers, especially that of religious liberty. "I think Mr. Smith is a person of humility and patriotism and enlightened philanthropy," Jordan said.

Smith's father, the late real estate developer Charles E. Smith, was a native of Russia who immigrated to New York in 1911. After a series of unprofitable building ventures, Charles E. Smith Cos. finally took off in 1946. The business developed residential, office and retail buildings in the Washington area and -- on son Robert's advice -- developed the Crystal City complex of apartments and commercial real estate. The residential side of the business merged with Archstone to form a nationwide apartment owner, Archstone-Smith, and the commercial side of the business was sold to New York-based Vornado Realty Trust in 2002.

Jordan said the Smiths have been longtime supporters of the Thomas Jefferson Foundation, having given about $6 million previously. The largest gift to the foundation had been $10 million in the late 1990s.

Robert H. Smith has given at least $18 million to the University of Maryland at College Park's business school and also has served as president of the National Gallery of Art. He declined requests for an interview.