Magna Carta Rediscovered has toured Kent throughout the anniversary year.
But at Rochester Cathedral from Saturday the exhibition is showing Magna Carta alongside Textus Roffensis - which experts believe was the "grandfather" of Magna Carta itself.
Textus Roffensis was compiled in Rochester in the 1120s. Magna Carta was sealed in Runnymede, Surrey, in 1215.
A spokeswoman for Rochester Cathedral said Textus Roffensis contained the first recorded English laws and the Coronation Charter of Henry I.
She said the Coronation Charter later influenced the rebel barons who drafted Magna Carta and struck a deal with King John.
Textus Roffensis will be shown alongside Faversham's 1300 edition of Magna Carta, which still has King Edward I's seal attached.
Later editions of Magna Carta were drawn up in the years following the original 1215 treaty and it is thought seven 1300 editions survive.
Magna Carta protected the rights and freedoms of society and established that the king was subject to the law.
Its influence can be seen in other documents across the world including the UN Universal Declaration of Human Rights, and the US Constitution and Bill of Rights.
Why are there so many Magna Cartas?
Two rare manuscripts have been brought together in an exhibition marking 800 years of Magna Carta.