The Queen will retrace the footsteps of her Plantagenet predecessor today, visiting Runnymede as part of a series of events to mark the 800th anniversary of the signing of Magna Carta.
The Duke of Edinburgh, the Duke of Cambridge, Princess Anne and her husband Vice Admiral Sir Tim Laurence will join Prime Minister David Cameron and other dignitaries around the world as they visit the Surrey site where King John sealed the original document in 1215.
The Royal Barge Gloriana – leading a flotilla of 200 boats along the River Thames from Hurley in Berkshire - will pass through Old Windsor Lock on the River Thames in commemoration of the event.
The formal ceremony will take place from 9:15am, though entertainment including musical and spoken word performances started as early as 7am.
The Great Charter is widely seen as having played a hugely important role in the establishment of key freedoms enjoyed in democratic societies around the world, including setting the foundations of the principle of Habeas Corpus. However, as our timeline shows, the original document was not the end of the process.
Today a major new art installation, by Hew Locke, will be unveiled in the Runnymede meadows, and a rededication of the existing memorial, donated by the American Bar Association.
The new work, called The Jurors, was inspired by the 39th clause of Magna Carta, which gives the right to a jury trial.
Artist Hew Locke said it was a "great honour" to be chosen to produce the piece.