The British Library is to bring together four surviving copies of the original Magna Carta for the first time in history to mark the 800th anniversary of King John's royal charter.
The documents, which provided the cornerstone for the British constitution, will be held at the museum in London for three days in 2015.
Magna Carta, or "Great Charter" in Latin, was the first document forced on to a King of England by a group of his subjects, the feudal barons, in an attempt to limit his powers and protect their privileges. Signed by John at Runnymede, Surrey, in 1215, it established important principles that have been copied around the world. These included the idea that no one is above the law - including the king - the right to a fair trial, and limits on taxation without representation. Numerous copies, or "exemplifications," were made each time the charter was updated and issued in later years. Only four copies of the 1215 original survive - two are kept at the British Library, one is at Lincoln Cathedral and the fourth is at Salisbury Cathedral.
Claire Breay, lead curator of medieval and earlier manuscripts at the British Library, said: "Magna Carta is the most popular item in the library's treasures gallery, and is venerated around the world as marking the starting point for government under the law.
"Bringing the four surviving manuscripts together for the first time will create a once-in-a-lifetime opportunity for researchers and members of the public to see them in one place, and will be a fantastic start to a year of celebrations."
Magna Carta was written in Latin on parchment. Within 10 years, a third of the clauses had been dropped or rewritten, with almost all repealed in modern times. However, the library said it remained "a cornerstone of the British constitution and its principles are echoed in the US constitution and others around the world".
Bringing the originals together will allow researchers to study them side-by-side and attempt to identity the unknown writers of the texts.
The Dean of Salisbury, the Very Reverend June Osborne, said the charter's clauses on social justice were "as relevant today as they were 800 years ago".
The Very Reverend Philip Buckler, Dean of Lincoln, said bringing together all four copies would be of "national significance" and would mark a "pivotal point" in the anniversary year.
Lincoln Cathedral will be opening a new purpose-built Magna Carta centre in Lincoln Castle during the anniversary year.