President McAleese and the Taoiseach were at the Royal Hospital in Kilmainham this morning for a ceremony to mark the National Day of Commemoration.
The occasion was in memory of all Irishmen and women who have died in wars or on service with the United Nations.
Representatives from the Catholic, Presbyterian and Methodist Churches, the Church of Ireland and from Islamic and Jewish communities conducted a multi-faith commemoration to start the proceedings.
50 years of European unity will also be celebrated today, at an occasion at the Farmleigh estate in the Phoenix Park.
The event, which began at 10am, took the form of an open family fun day.
A major feature is the EU Village, which offers a variety of cultural and culinary experiences from all the EU member states.
The Minister of Foreign Affairs, Dermot Ahern, has said that since Ireland's accession to the EU in 1973, the State had greatly benefited from membership, and has significantly contributed to its development.
Mr Ahern added that it was important to involve young people in the celebrations.