The Olympic Torch arrived in Belfast on Saturday night at the start of a six-day visit to Ireland.
It will cover the north coast, home of golf's former US Open winner Graeme McDowell and this year's Irish Open, 2013 City of Culture Londonderry and Dublin in a symbol of Anglo-Irish goodwill.
Police in Northern Ireland warned that the terrorism threat level remained severe and appealed for public vigilance.
Former Olympian Dame Mary Peters, who won gold at the pentathlon in 1972, was at Belfast City Airport to greet it off the plane.
Also at a reception were blind water skier Janet Gray, First Minister Peter Robinson, Deputy First Minister Martin McGuinness and Northern Ireland Secretary Owen Paterson as well as local schoolchildren.
A sign with the slogan "Inspire A Generation" flew outside the airport.
The security forces will be on high alert during the visit.
Police Service of Northern Ireland Assistant Chief Constable Alistair Finlay warned people to be alert.
He said: "There is always that small group of people intent to cause disruption and harm to the community. The threat remains severe and police officers remain the principal target.
"The additional police presence during this time will provide a greater opportunity for those people intent on attacking us and we will have to protect ourselves and the community.
"We would ask our communities to be vigilant over the coming period and to help us to protect you."
A beaming Dame Mary carried the flame in a golden Olympic lantern through an arrivals hall packed with cheering, flag-waving children.
She said she would be attending her 12th Games in London.
"Thank you for sharing those magical moments with us. It is our moment to shine and I want you to bring your friends out on the streets to appreciate what this means to all of us," she said.
Mr Robinson said it was a privilege to welcome the flame to Northern Ireland and witness its journey over the coming days.
"It will be carried by 400 torchbearers through cities, towns and villages, past many of our iconic landmarks, creating what promises to be a once-in-a-lifetime spectacle for all to see," he said.
Mr McGuinness said: "The all-Ireland torch relay epitomises the values and spirit of the Olympics. The Olympics are a celebration of sport, culture and local heroes. It is great that we are playing our part in this celebration."
Among sporting figures expected to carry it are Olympic boxing medallists Wayne McCullough and Michael Carruth who will take part in the hand-over at the border.
Other highlights are a celebratory event at St Stephen's Green in Dublin city centre on Wednesday and the crossing of the newly built Peace Bridge in Londonderry, linking the mainly nationalist west of the city with the mainly unionist east.
Celebrities taking part in the relay include Northern Ireland-born television personalities Zoe Salmon, Patrick Kielty and Colin Murray.