By Georgie Keate
At some point between 10.30 and 11.30 BST, former IRA commander Martin McGuinness shook the hand of his once-nemesis, the Queen, in a historic act which will win headines around the world.
The act of reconciliation happened in a private room away from all the cameras, but the pair later repeated it as they said goobye outside the Lyric theatre.
The handshake has been heralded as a milestone for Anglo-Irish relations after decades of sectarian violence.
"The image of The Queen and Martin McGuinness shaking hands is a remarkable testament to all those who have contributed to building peace in Northern Ireland. Observers hope it will seal a long and arduous peace process between republicans and unionists," Vernon Coaker, Labour's shadow minister for Northern Ireland said.
"I know that Martin McGuinness and his colleagues will use this hugely symbolic moment to spur on their work to create a better future for everyone in Northern Ireland."
Mr McGuinness is now Northern Ireland's deputy first minister, having spent most of this life as a leading member of the IRA.
In 1979, the terrorist group murdered Prince Philip's uncle, Earl Mountbatten of Burma, while also conspiring against the Queen's life.
"Today, in this year of her Diamond Jubilee, Her Majesty has again shown a unique ability to provide inspiration to the entire country in her dignity and service to our nation," Mr Coaker said.
The 86-year-old monarch is on a two-day tour of the country where she visited Catholic church St Michael's.
There was also an event held at Enniskillen, the site of a devastating IRA attack in 1987 that killed 11 and wounded 63, where she was greeted with applause and people waving union flags.
The Queen is also scheduled to visit Belfast's Titanic exhibition and attend a party in Stormont involving 20,000 locals.