US vice-president Joe Biden will deliver a keynote speech today in the grounds of Dublin Castle as part of his six-day visit to Ireland.
In an outdoor event open to members of the public who applied for tickets, Mr Biden is expected to touch on the Irish-American experience, the shared heritage of the two nations as well as the values of tolerance, diversity and inclusiveness.
LGBT rights advocate Michael Barron will introduce the vice-president.
Traditional Irish band The Chieftains, singer-songwriter Mundy and Irish language band Seo Linn will also play at the event which has sparked a major security operation in the Irish capital.
Mr Biden is also expected at a number of engagements at Trinity College Dublin during the day, where he will receive an honorary doctorate as well as a gold medal from the university's philosophical society.
His return to Dublin follows two days in Mayo, in the west of Ireland, where he kept his promise to play a round of golf in Ireland.
Barack Obama's right-hand man battled blustery conditions around Castlebar Golf Club in Co Mayo - the Augusta of Connaught and Taoiseach Enda Kenny's home course.
And with a packed clubhouse looking on, the two men diplomatically halved the match on the 18th.
Two holes earlier, on the par three 16th, Mr Biden watched nervously as his tee shot narrowly missed a water hazard before hinting that the Taoiseach had the upper hand.
Asked how his golf game was going, the vice-president said: "It's going.
"Fortunately, politics is going better."
The round was organised as part of Mr Biden's long-awaited trip to his ancestral homeland, a private and personal visit designed for him to trace his roots before his term in office ends later this year.
He had also promised the tour of Ireland to his son Beau, a veteran of the Iraq war, who died last year from brain cancer before the commitment could be met.
It is understood the long-standing invite to play golf with the Taoiseach in Ireland helped instigate such a long and varied visit from the vice-president.
Ranked several years ago by Golf Digest at 29 in its list of Washington's top 150 golfers, Mr Biden plays with a handicap of 6.3 - up there with John F Kennedy as among the best the White House has seen.
And buoyed by the challenge of a parkland course rather than the wilds of Irish links, Mr Biden was part of a four ball with his brother Jimmy, Mr Kenny and Castlebar club captain Frank Murray.
In full glare of the cameras and members at the back of the 16th green, the vice-president landed his ball a yard from the pond but saved face with a steady chip out of the rough to the heart of the green.
The Taoiseach gave no quarter and he putted his second to within a couple of feet of the hole for the vice-president to call a "gimme".
Tom Prendergast, member of the Castlebar club and owner of the Village Inn in nearby Ballyvary, dismissed any sense of transatlantic rivalry on the fairways.
"It was a wonderful spectacle. Castlebar put on a great show," he said.
"The Taoiseach played some great golf but it was just a friendly."
A mountain ash tree was planted on the course to mark the rare event of a US vice-president playing a round of golf at the club.
A massive security operation was mounted around the golf club as the vice-president's 20-strong motorcade swept into town.
Overnight, secret service agents and gardai were on patrol around the course and stationed on every tee and green to secure the course for the visiting dignitary.
Mr Biden's ancestral connections with Co Mayo have been traced back as far as the late 1700s.
His great-great-great-grandfather Edward Blewitt lived in Ballina and great-great-grandfather Owen Finnegan, the Cooley peninsula in Co Louth, and both left Ireland during the Great Famine of the 1840s.
A trip to Co Louth on Saturday will also take in sites with ancestral links while Newgrange is also on the agenda.