The US President, Joe Biden, has said it is a “pleasure to be back” as he met Irish President Michael D Higgins in Dublin.
He is spending most of Thursday in the company of leading Irish politicians.
He started his working day with a visit to Áras an Uachtaráin – the home of the Irish president in Phoenix Park.
President Biden inspected a military guard of honor, and signed the visitors’ book. He also planted an oak tree and set the Bell of Peace.
The bell was erected in 2008 to commemorate the tenth anniversary of the Good Friday Agreement.
After ringing the bell, President Biden gave it another ring, saying: “One more for peace”.
He said he was feeling “great” and that he had “learned a lot from the president”.
President Higgins then gave President Biden a quick tour of the grounds around his official residence and introduced him to one of his dogs.
President Biden met Taoiseach (Irish prime minister) Leo Varadkar at nearby Farmleigh House.
The two leaders shook their hands and exchanged a few words before posing for pictures.
Mr. Biden remarked that it was “a beautiful day”, the weather was a contrast to the conditions that greeted him as he arrived in Dublin on Wednesday.
Mr Varadkar said it was “great” to have the US President back in Ireland and that the visit was going “very well”.
Mr Biden described the meeting as an opportunity to make “tremendous progress”.
He said he was not just commemorating the 25th anniversary of the Good Friday Agreement – but also wanted to hail Ireland’s “leadership” on world issues such as taking in Ukrainian refugees.
Earlier, Mr. Biden said he had quoted an Irish proverb, in his message in the visitors’ book – “your feet will bring you where your heart is”, adding that it was “an honor to return”.
He made a reference to returning to the home of his ancestors, pledging to commit to peace, equity and dignity.
Mr Biden added: “I’m not going home. Isn’t this an incredible place, all you American reporters, it’s just like the White House, right?”
A delegation attending the event included Tánaiste (Irish deputy prime minister) Micheál Martin, US Secretary of State Anthony Blinken and former Irish football star Paul McGrath.
President Biden’s visit to Ireland will continue with set-piece engagements, including an address to the Irish parliament.
His visit to the Republic of Ireland encompasses both the personal and the political.
On Wednesday evening it was all about the personal.
President Biden visited both Dundalk and his ancestral roots in the town of Carlingford in County Louth.
Mr. Biden met distant relatives in the Cooley Peninsula, where crowds lined the quayside as the presidential motorcade arrived.
Later in Dundalk, there were shouts of “welcome home, Joe” when Mr. Biden arrived to address an audience at the town’s Windsor Bar.
He said Irish people were the “only people in the world in my view who are actually nostalgic about the future”.
A major security operation is also under way in the Republic of Ireland’s capital, with a number of city center roads closed.
Polythene wraps have also been placed around bins along the route the US president will take.
Phoenix Park is shut until 17:00 local time on Thursday, with pavements near Dublin Castle shut for pedestrians until midnight on Friday.
Mr Biden was to be given a sample of Gaelic sports with a demonstration by young players before traveling to Leinster House to address both the houses of the Oireachtas (Parliament) – the Dáil and the Seanad (Senate).
His speech is expected to emphasize both his pride in his Irish roots and American support for the Good Friday Agreement – which is 25 years old this week.
Former Irish president Mary McAleese, former taoiseach Bertie Ahern and some Stormont party leaders are among those expected to attend.
Marie Heaney, the widow of the late poet Seamus Heaney, will be a special guest of the US President, Irish national broadcaster RTÉ reports.
“He was most anxious that she would be present as part of his delegation because we know he is absolutely besotted by the work of Seamus Heaney and has quoted him extensively,” Ceann Comhairle (speaker) Seán Ó Feargháil said.
After his speech, President Biden will be the evening guest of honor at a state function in Dublin Castle, the former seat of British power in Ireland.
On Wednesday, the US President met political leaders in Northern Ireland at the new Ulster University Belfast campus.
He called for politicians to restore the power-sharing government at Stormont, which collapsed more than a year ago.
He was praised by politicians for their unity after the attempted murder of one of Northern Ireland’s top detectives in February.
John Caldwell was shot several times by two gunmen in Omagh, County Tyrone.
On Friday, the US President is expected to travel to County Mayo where he will again explore his Irish ancestry.
His great-great grandfather Edward Blewitt left Ireland around the time of the famine.
While in the county, the President, who is a Catholic, is also expected to visit the shrine at Knock and to make an outdoor speech to people in Ballina before he ends his four-day visit to the island.
A US genealogist who researched Mr. Biden’s lineage had estimated he is “roughly five-eighths” Irish.
His great-great grandfather Owen Finnegan left there for America in the late 1840s.
Declan Harvey and Tara Mills explore the text of the Good Friday Agreement – the deal which heralded the end of the Troubles in Northern Ireland.
They look at what the agreement actually said and hear from some of the people who helped get the deal across the line.
Listen to all episodes of Year ’98: The Making of the Good Friday Agreement on BBC Sounds.