Red Arrows in Belfast fly-past to herald Olympics
The Red Arrows have performed a fly-past over Belfast to mark the start of the Olympic Games.
Earlier, the bells on Londonderry's two cathedrals and those at two venues in Belfast rang out in harmony in celebration of London 2012.
Thousands of bells were rung across the UK as everyone was encouraged to ring some kind of bell for three minutes, beginning at 08:12 BST.
The opening ceremony will be shown on the big screen at Belfast City Hall.
The council will also be hosting an evening of entertainment on Friday from 19:30 BST in the City Hall grounds which includes music, fire performers, carnival drummers and acrobats.
The Red Arrows are doing a fly-past in each of the four UK capital cities.
They flew over City Hall, up Donegall Place and out over south Belfast just after 13:00 BST on Friday.
Lord Mayor of Belfast Alderman Gavin Robinson said: "The opening ceremony promises to be a spectacular occasion as we look forward to a summer of sport with the Olympics and Paralympic Games.
"A cast of thousands is taking part in the ceremony and I think it's fitting that the live site at City Hall will be broadcasting the event to give everyone a chance to feel part of the excitement.
"There will also be a daily schedule of live coverage of the games so we can cheer on our home-grown sporting talent."
The opening ceremony is scheduled to finish at midnight.
Those attending Friday's celebrations in Belfast are being encouraged to take part in an Olympic sing-along as part of the opening ceremony.
Olympics coverage online
There will be daily coverage of the Olympics on the big screen until about 23:00 BST each evening.
Meanwhile, bells also rang out at St Columb's Cathedral and St Eugene's Cathedral in Derry, as well as at St George's Market and City Church in Belfast as part of the UK-wide celebration.
There was also some music-making on the roof of BBC Broadcasting House in Belfast.
Irish Prime Minister Enda Kenny is in London to meet members of the Irish team, at their pre-Olympic training camp on Friday.
Mr Kenny is also attending a reception hosted by the Queen at Buckingham Palace, before heading to the Olympic Stadium for the opening ceremony at 19:30 BST.