Siptu will host a programme of cultural events to commemorate the 1916 Rising and the role that its headquarters Liberty Hall played in it.
The events will include a gala concert there tonight featuring Christy Moore and Damien Dempsey and talks on Easter Monday.
On Tuesday, President Higgins will lay a wreath at the James Connolly statue on Beresford Place in a state commemoration of those who lost their lives in the Irish Citizen Army and afterwards will unveil a plaque at the Hall.
Frank Connolly, Head of Communications with SIPTU, explains the role of the site in the rising.
He said: "The Citizens Army and the Volunteers assembled at Liberty Hall to go to the GPO and other places of resistance and occupation.
"It was also the place where the Proclamation was printed and where preparations for the Rising were made. It was shelled in the days after the Rising."