With the 800th anniversary of Magna Carta quickly approaching, I thought this was really fascinating. It says that "the document was ripped with about a third missing but could still be worth up to £10m, according to Professor Nicholas Vincent, a specialist in medieval history from the University of East Anglia.
"Its high value comes from the fact that it was found with the Charter of the Forest. The only other such pair - dating from 1300 - in the world is owned by Oriel College, Oxford."
You can read more about it here: http://www.bbc.com/news/uk-england-31242433