A 13th century copy of the Magna Carta manuscript sold for more than £10 million at auction to an American businessman who said it will remain on public display.
David Rubenstein, co-founder of private equity firm The Carlyle Group, paid $21.3 million (£10.6m) when the document went under the hammer at Sotheby's in New York.
A photo issued by Sotheby's of the 13th century manuscript
Dated 1297, the royal document - described as "the most important document in the world" - was one of just 17 copies still in existence and the only one in private hands.
Mr Rubenstein, who worked in the White House in the Carter Administration, said after last night's auction: "Today is a good day for our country. "I am an American citizen; I work in Washington, DC, 300 feet from the National Archives and I visited the Magna Carta there several times.
"I was moved when I saw the manuscript at Sotheby's and I was concerned that the only copy that was in America would escape. I was convinced that it needed to stay here. "This document stands the test of time. There is nothing more important than what it represents.
"I am privileged to be the new owner, but I am only the temporary custodian. This is a gift to the American people. It is important to me that it stays in the United States.
"I have always believed that the three most important documents were the Constitution, the Declaration of Independence and the Magna Carta."
A Sotheby's spokeswoman said the Magna Carta had been "saved for America" by Mr Rubenstein, who intends to place the document back on view at the National Archives in Washington, DC.
The Magna Carta, which is Latin for Great Charter, was initially issued in 1215 but not confirmed as English law until 1297.
David Redden, vice-chairman of Sotheby's, said it was "the most important document in the world".
"The 1297 MagnaCarta became the operative version, the one that was entered into English common law and became the law of the land," he said.