A copy of the Magna Carta-the declaration of the human rights- was sold for $21.3 million on Tuesday at Sotheby’s auction.

The declaration is a 710-year-old copy and is the version that became part of the English law, CNN Money informs.

The document was bought by David Rubenstein, a Washington businessman, of the Carlyle Group, according to the spokeswoman of Sotheby.

In September, when the auction was announced, Magna Carta was evaluated at $30 million.

The document was called by David Redden Sotheby's vice chairman "the most important document in the world, the birth certificate of freedom."

This is one of the 17 copies known to exist and the last one that exists in the United States. It is also the last to be in the hands of a private owner, Reuters informs.

The document was sold by the Perot Foundation, created by Texas billionaire H. Ross Perot. The Perot Foundation acquired it for $1.5 million from Brudenell family of Deene Park in Northamptonshire in 1984.

The document was on display at the National Archives in Washington from 1988 until this year. It shared the space with other two documents for which it served as inspiration: the Declaration of Independence and the U.S. Constitution.

Rubenstein said that he bought it only so that it can remain on display at the National Archives.

He said: "I am really just a temporary custodian of it."

The document is dated 1927 and it bears the seal of King Edward I. It is one out of the two that exist outside of Great Britain. The second one is in Australia.

Redden said that the document was possibly seen by 40 to 50 million people while it was on display at the National Archives.

The Magna Carta was created by a group of English barons who forced their king, John, to sign it in 1215. In the next 80 years it suffered modifications brought by successors of King John, and in 1297 it was passed as a law by King Edward I.

The price from the auction on Tuesday included Sotheby’s commission.