The leader of the Democratic Unionist Party, Arlene Foster, has confirmed she will attend the funeral of Sinn Féin’s Martin McGuinness later.
Ex-US President Bill Clinton, the Irish president and the taoiseach (Irish prime minister) are also set to attend.
The former IRA leader turned politician died on Tuesday after a short illness.
The streets of Londonderry are expected to be crowded with mourners during the service at Saint Columba’s Church Long Tower.
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Before the ceremony, the same church is hosting the funeral of the Derry City Football Club captain, Ryan McBride, who died suddenly on Sunday aged 27.
Irish President Michael D Higgins will attend both funerals and the Irish Tricolour will fly at half mast at his official residence Áras an Uachtaráin as well as the Dáil (Irish parliament) as a mark of respect to Northern Ireland’s former deputy first minister.
The Northern Ireland Secretary of State, James Brokenshire, will represent the UK government at Mr McGuinness’ funeral.
Former US President Barack Obama has added his voice to tributes to the former Sinn Féin minister, saying his leadership was “instrumental” during the peace process.
‘Respect to his family’
Mr McGuinness’s later life was marked by moments which banished long-held shibboleths – in particular his handshakes with the Queen., says BBC News NI political editor Mark Devenport.
Now his death will provide another striking image – of a DUP leader and IRA victim attending the funeral of a former IRA commander.
Writing in the Belfast Telegraph, Mrs Foster said she recognised some will be critical of her decision to attend the funeral of a former IRA leader but added she wanted to pay “respect to his family”.
Analysis – BBC News NI political editor Mark Devenport
Before he died Martin McGuinness was strongly critical of Arlene Foster for – in his view – not matching his gestures of reconciliation.
So the sight of the DUP leader attending Mr McGuinness’s funeral may be seen as an attempt by Mrs Foster belatedly to make amends.
As someone whose father was targeted and whose school bus was blown up by the IRA, it’s understandable that Mrs Foster may have had to think hard about this decision.
It’s likely she will have sought assurance there will be no paramilitary trappings.
Mr McGuinness, who was 66, had been suffering from a rare heart condition.
He died at Altnagelvin hospital in his native city of Derry, with his family by his bedside.
Many tributes from across the political spectrum have been paid to the former paramilitary leader who became the deputy first minister of Northern Ireland.
However, some victims of the Troubles have expressed revulsion at media coverage of his death, with critics saying that Mr McGuinness was lauded as a peacemaker despite never having apologised for his IRA past.
Mr McGuinness, who was at one time the IRA’s second-in-command in Derry, was later appointed as Sinn Féin’s chief negotiator in the talks that led to the 1998 Good Friday Agreement.
He has been hailed as one of the architects of the historic peace deal, which helped to end nearly three decades of political unrest and sectarian violence.
Mr Clinton was in office at the time and the then US president dedicated a considerable amount of time and resources to assist the negotiations.
The talks were chaired by Mr Clinton’s Special Envoy to Northern Ireland, former Senator George Mitchell.
Mr Obama, who also visited Northern Ireland during his presidency, said Mr McGuinness was “a man who had the wisdom and courage to pursue peace and reconciliation for his people”.
“His leadership was instrumental in turning the page on a past of violence and conflict that he knew all too well.
“In our own meetings, I was always struck by his good humour and persistent belief in a better future for the people of Northern Ireland.
May Martin rest in the peace that he pursued in life, and may his example inspire others to follow a path of reconciliation.”
Unionist leaders have acknowledged the important role Mr McGuinness played in the peace process, but also said his death on Tuesday was a difficult day for IRA victims.
At a special sitting of the Northern Ireland Assembly on Wednesday, Mrs Foster said while “many victims are feeling very hurt”, she acknowledged that many republicans were mourning “a leader, a friend, or a mentor”.
Sinn Féin’s northern leader, Michelle O’Neill, described Mr McGuinness as a “political visionary”.
One of Mr McGuinness’ last political acts was to resign as deputy first minister of Northern Ireland, over Mrs Foster’s handling of a green energy scandal.
Under Northern Ireland’s power-sharing structure, the joint nature of their office meant that when he quit, she also lost her position as first minister.
The move led to a snap election on 2 March, the result of which ended the unionist majority at Stormont.
Foster and Clinton to attend McGuinness funeral}