爱尔兰总统首次访英
The first official visit to the UK by an Irish head of state is due to get under way.
爱尔兰国家领导人对英国的首次正式访问即将启动。
The Queen shook hands with Martin McGuinness during a trip to Belfast two years ago
President Michael D Higgins will meet the Queen and address Parliament - another historic first.
Ahead of the trip he said Anglo-Irish relations were at a high but warned there was "significant work" to do secure peace in Northern Ireland.
Ireland won independence in 1921 following a civil war and guerrilla campaign against British forces.
However, six counties were kept under British control, creating Northern Ireland.
For centuries Ireland was under British or English rule and the more recent troubles can be traced back to the partition of the country.
President Higgins said there were "a lot of very difficult memories" and that it would be wrong to "wipe the slate clean".
His trip comes after the Queen became the first British monarch to visit the Republic of Ireland three years ago.
Then Sinn Fein did not take part, but Northern Ireland's Deputy First Minister and former IRA commander Martin McGuinness will attend a banquet hosted by the Queen at Windsor Castle on Tuesday.
Mr Higgins said: "I think Her Majesty in coming to Ireland and addressing for example issues of relations between our two people was doing it the right way."
The statesman, who came to England to work as a waiter when he was 21, said his visit would be "very important for the relationships between the people of Ireland and UK".
"My hope for the visit at the end of it all is that people will in ever more numbers come to share in experiencing the history, the present circumstances and culture, and do so in ever greater numbers."