The Queen is expected to hold a private meeting with Northern Ireland deputy first minister and former IRA commander Martin McGuinness as part of her two-day visit to Northern Ireland.
This will be the first meeting to ever take place between a monarch and a member of Sinn Fein, the political wing of the IRA.
The Queen is expected to shake hands with McGuinness in what is being viewed as a defining moment of the Anglo-Irish relationship.
Ironically, their meeting is due to take place on 27 June, 25 years after the Queen met relatives of the victims of an IRA bombing in Enniskillen.
McGuinness is a former commander of the organisation that was responsible for murdering the Queen's cousin and Prince Philip's uncle, Lord Mountbatten, in a bomb blast aboard his boat in Mullaghmore in 1979.
Thomas McMahon, a former IRA volunteer who planted the bomb, currently lives in county Monaghan and has reportedly declined to speak to the media about the Queen's visit.
The Queen will meet with McGuinness on neutral territory at an arts event in Belfast as part of her diamond jubilee tour. The event has been organised by the charity Cooperation Ireland and will also be attended by Irish President Michael D Higgins.
The meeting between the Queen and McGuinness is highly anticipated as a momentous step in Anglo-Irish relations.
"From my perspective it's a huge act of reconciliation, you cannot underestimate how important this is. Whoever would have thought we would ever be in this situation - it says a lot about healing, human dignity and treating each other with respect. After today all of us will say things have changed - for me that's the significance of it," said Peter Sheridan, chief executive of Cooperation Ireland, according to the Press Association.
The Queen is expected to hold a private meeting with McGuinness and will be accompanied by Prince Philip on her visit to Ireland.
The royal couple will also travel to Stormont in Belfast, where an estimated 20,000 people are expected to attend a garden party to celebrate the Queen's diamond jubilee.