Pope Francis has confirmed he will make the first papal trip to Ireland in nearly 40 years and will visit Dublin this summer.
The World Meeting of Families is taking place in Dublin from August 21-26.
The Pope (81) will preside at the closing ceremonies on the final two days.
He will take part in the Festival of Families in Croke Park on August 25 and the following day he will celebrate Mass in the Phoenix Park.
The Pope announced the visit to tens of thousands of people in St Peter's Square for his weekly audience.
The confirmation of his two-day visit to Dublin appears to rule out a papal visit to Northern Ireland. However, insiders have said it is still possible.
One senior source stressed that the Pope's full schedule will not be confirmed until June.
Taoiseach Leo Varadkar has welcomed the announcement by Pope Francis.
"I look forward to meeting him during his visit," the Taoiseach said.
His statement added that while it is not a formal State Visit, it will be a major event for Ireland, with a high degree of public participation and a high international profile.
The Irish Catholic Bishops' Conference welcomed the news and said they are "deeply honoured" that the pontiff has chosen to come to Dublin.
"We are deeply honoured that Pope Francis will come to our country to participate in this universal Church celebration of faith and joy, as well as of the contemporary challenges which face families," the bishops said in a statement.
Garda management is expected to put together a significant security operation for the visit of the Pope, involving highly-trained snipers and bomb sweeps.
The security plan will be on par with similar operations put in place for the visits of Britain's Queen Elizabeth and then US President Barack Obama by the garda's Liaison and Protection branch.
While garda management has not yet received an itinerary from the Pope's representatives in Rome to draw up formal plans, up to 20 members of the Emergency Response Unit (ERU) will accompany him on a 24/7 basis.
The officers are part of the new Close Protection Unit, set up this year under Special Tactics and Command (STOC) to ensure the safety of VIPs.
These suited detectives will be fully armed as they travel with the pontiff - whose representatives will bring their own armoured vehicles from Rome.
Bomb sweeps and general security checks of locations and venues will also be carried out by ERU officers - known as a special advance team - prior to the arrival of the Pope.
As with the visit of the queen and President Obama, drains will be welded shut on any travel routes to prevent bombs being placed in the sewers.
The Garda Water Unit will also patrol the River Liffey during the papal visit.
Snipers attached to the ERU will also take up positions on roof-tops when the Pope is out in public.
A source said that including snipers and bomb sweeps was "standard protocol" for the visit of a high-profile VIP, and that there is no intelligence to suggest there is a threat against the Pope when he visits Ireland.
Yesterday in Rome, two Irish families - the Tobins from Co Kildare and the Bushells who live in Rome - were selected to present the official World Meeting of Families 2018 Icon of the Holy Family to Pope Francis during his weekly general audience in St Peter's Square, in a delegation led by Archbishop Diarmuid Martin.