In the 800th anniversary year of the sealing of the Magna Carta, another copy has been found - after lying unnoticed in a council's archives for decades.
The document was discovered by Kent archivist Dr Mark Bateson, who was hunting through the files for a different charter, Sandwich's Charter of the Forest.
He finally found it lurking in a Victorian scrapbook - with the Magna Carta alongside. "It has been badly damaged by damp, missing about a third of its text, and its royal seal has also disappeared," says Sophie Ambler of the Magna Carta Project.
However, it's still believed to be worth as much as £10 million, because it comes with the Forest Charter - there's only one other such pair known. However, Sandwich Town Council says it has no plans to sell the document, but intends to keep it as a tourist attraction instead.
"On behalf of Sandwich Town Council, I would like to say that we are absolutely delighted to discover that an original Magna Carta and original Charter of the Forest, previously unknown, are in our ownership," says Paul Graeme, mayor of Sandwich Town Council.
The first Magna Carta was drafted by the Archbishop of Canterbury and sealed by King John on June 15, 1215 to make peace with a group of rebel barons. It establishes basic rights, and the principle that nobody is above the law, not even the king.
It promises the right to a fair trial, and was the inspiration for a number of other documents, including the US Constitution and the Universal Declaration of Human Rights.
Magna Carta was reissued a number of times in the years that followed, with the newly-discovered Sandwich version issued by Edward I in 1300.
Twenty-four editions of the Magna Carta are now known to exist. However, Professor Nicholas Vincent, of the University of East Anglia, who authenticated the document, believes that it may have been circulated to as many as 50 cathedral towns and ports.
So there may be more copies out there, he says.
"It is a fantastic piece of news for Sandwich which puts it in a small category of towns and institutions that own a 1300 issue," he told the London Evening Standard.
"And it is very likely that there are one or two out there somewhere that no one has spotted yet."
Read more on AOL Money:
Fancy a £4m private island - in Berkshire?
Cathedrals among budget winners
Tiny book of psalms sells for £8.7m