NEW YORK - A rare 710-year-old copy of the Magna Carta, among the most important historical documents ever to hit the auction block, sold for $21.3 million (10.6 million pounds) on Tuesday at Sotheby's.

The document was bought by a Washington businessman who said he was determined to see it remain in the United States, where it has been on display at the National Archives and Records Administration since 1988.

The last remaining copy in the United States and the last in private hands, the Magna Carta, one of 17 known to exist, was sold by The Perot Foundation, created by billionaire former U.S. presidential candidate Ross Perot to make philanthropic grants. The foundation acquired it from the collections of the Brudenell family of Deene Park in Northamptonshire in 1984.

"It's a good day for our country," said David Rubenstein, a lawyer and founder of The Carlyle Group, a private equities firm, told reporters after he made the extraordinary purchase, adding that he had arrived just minutes before the sale and very nearly missed out.

"I was determined to do what I could to see that the National Archives can continue to display this," Rubenstein said, noting that the 1297 document was the basis for both the U.S. Constitution and the Declaration of Independence.

"I am really just a temporary custodian of it," said Rubenstein, adding that he would not have to travel far to see the document as his office is just a few hundreds yards from the National Archives. Rubenstein said his Washington connections run deep, having once worked under President Jimmy Carter as a deputy domestic policy advisor.

He said he would "rely on the National Archives' advice" regarding the document possibly going on tour internationally, saying his wish was that it could be seen by as many people as possible.

The Magna Carta, which Sotheby's called "the most important document in the world," established the rights of the English people and curbed the power of the king.

The U.S. Constitution includes ideas and phrases taken almost directly from the charter, which rebellious barons forced their oppressive King John to sign in 1215.

Sotheby's said the Magna Carta was ratified and reissued with each monarch who succeeded John. It was enacted as law in 1297 by the British parliament when it was reissued by King Edward I. The copy sold on Tuesday is from 1297.

Asked how high he was willing to bid for the Magna Carta, Rubenstein replied: "I don't think you can put a price on freedom."

When it announced the auction in September, Sotheby's said the document was valued at up to $30 million. The final $21,321,000 price included Sotheby's commission.

The record for a document or manuscript at auction is held by Leonardo da Vinci's "Codex" manuscript, which sold for $30.8 million at Christie's in 1994.

Magna Carta, which has been in display at Sotheby's since December 7, will remain on public view at least through Wednesday.