The Queen and Northern Ireland's Deputy First Minister Martin McGuinness are to tour one of the most notorious prisons of the so-called Troubles.
McGuinness and the First Minister, Peter Robinson, were both detained in Crumlin Road Goal at Her Majesty's Pleasure - and both will be showing the Queen around the prison today.
The Queen last visited Northern Ireland in 2012 as part of her Diamond Jubilee celebrations and the was the first time she publicly met controversial figure McGuinness.
The former IRA leader was a guest at Windsor Castle in April this year. After his private meeting with her yesterday, he praised the Queen for her continued to efforts to aid reconciliation by taking part in "bold gestures".
Democratic Unionist Party leader Peter Robinson was locked up four times during the 1980s for protesting against the Anglo-Irish Agreement.
McGuinness found himself behind bars in the Crumlin for six weeks in 1976 after he was accused of having IRA membership.
After she has visited the jail, the Queen and the Duke of Edinburgh will continue their day on a lighter note - by touring the Belfast set of Game of Thrones.
The popular TV show is believed to have boosted the local economy by £87m over its four seasons.
One of the biggest television productions in Europe, Game of Thrones has created 900 full-time, and close to 5,700 part-time jobs.