There were concerns about the culture clash between Northern Unionists and Republicans from the South. But Conor Popetoday witnessed clashes of an entirely different kind.
A great cheer goes up as the beautifully maintained Vespa scooter parked on O'Connell St is kicked onto its side and torched by three teenagers wearing hoodies and scarves.
Other similarly clad youths, after being momentarily distracted by the conflagration, return to the matter at hand - trashing bicycles and breaking breeze blocks into pieces of a sufficient size to throw at gardai.
One rioter finds a wheelbarrow on that part of the street which remains a building site. He runs towards the line of police and when just feet away he hurls it violently at a garda's head. He manages to deflect it with his shield and, unhurt, stands his ground. Another cheer rises from the crowd.
Amidst the violent scenes two women and a man carrying a painting of the Virgin Mary head fearfully in the direction of the police line. The route they are following along O'Connell St is part of a regular procession they take through the city centre.
"Walk behind me." says one of the ladies to the man. "Once they see what we are at they will let us through," she says nodding in the direction of riot squad. She is very wrong. There is absolutely no chance they will be allowed cross the line and they take a diversion up Sackville Place.
They pass a man with blood streaming down his face. His friend suggests he seeks medical attention. "I can't go and leave my soldiers alone," he says without a trace of irony. The "soldiers" meanwhile continue to throw empty cider bottles at gardai.
"We don't want them walking down our main street," one of the protesters says referring to the Love Ulster parade. "We have been forced to do this. They are not wanted here. We don't want to be fighting on O'Connell St, we don't want to wreck our city. We don't want to be fighting the guards. But we don't want these people walking down our street. They have blood on their hands."
Another protester, with blood on his head, agrees. "I'm here for Ireland," he says, slightly incoherently. He tries to lay the blame for the riot squarely at the door of the gardai. Suddenly a missile thrown at random by one of his compadres strikes this reporter on the face. Nothing is damaged bar the protesters claim that the garda are responsible for the violence.
Another, more sober protester calls the whole scene a disgrace. "It is a disgrace that it is happening on O'Connell St. It is a disgrace the Fianna Fail allowed it to happen. I would gouge my eye out with a spoon before I ever vote for Fianna Fail again he says. "If the people who founded this country in that building," he says gesturing towards the GPO, "could see this they would be turning in their graves." He is not talking about the riot but the aborted parade.
The serious violence moves suddenly, as if by osmosis, towards Nassau St, just yards from the scene where one of the bombs planted by loyalists went off in Dublin in 1974. Two cars are on fire, torched by rioters angry at having their path to Kildare St and Dail Eireann - where unionists are rumoured to have gathered - blocked by riot police and gardai on horseback.
The mood here is more tense and more ugly than it was on O'Connell St, with the narrow street lending the atmosphere a claustrophobic air. The cars are allowed burn unattended and look to be a danger to nearby buildings. The gardai are forced to take action and start moving the line back. There is blind panic as the rioters, tourists and passers-by accidentally caught up in the violence turn and run towards Grafton St.
A small group of rioters take a left turn off Nassau St and head up South Frederick St. "Up this way. Come on would yiz, up this way," one youth wearing a Celtic shirt and a scarve around his face shouts.
There is confusion for a moment as some of those fleeing slow, stop and follow his lead. They start stoning a building and launching metal barricades at the windows. It is the headquarters of the Progressive Democrats.
At the top of the city's main shopping street, tourists quiz gardai as to what is going on and ask for directions. One Welsh couple, over for tomorrow's rugby match, ask a garda sergeant how to get to O'Connell St. Ruefully he shakes his head and tells them, "you'd be as well off avoiding the city centre for now". Nearby, on Suffolk St, group of school children start to cry when they see the crowd running in their direction. For a moment the situation looks like spiralling even further out of control.
A fresh line of gardai - without riot gear - arrive on the scene. They look distinctly vulnerable but the rioters look intimidated and slowly dissipate. The school children stop crying and the majority of shoppers seeing the line of guards, turn and head in the direction of St Stephen's Green.
It's not so calm on O'Connell Bridge, Westmoreland St and Aston Quay where the missiles continue to rain down on gardai. Scores of bottles are thrown as the riot police try to move the protesters away from the city centre towards the Ha'Penny Bridge.
Shoppers seek refuge in the narrow and unfamiliar streets off the quays. A golf ball, aimed at the garda line veers off course and strikes the wall of a narrow lane just off Aston Quay. It ricochets around like a pinball before striking a bemused Spanish tourist on the leg. Although unhurt she is still shaken by being unexpectedly caught up in a riot on a sunny spring morning in Dublin. "Que pasa?" she asks as she picks up the ball.
A lot of Dubliners were left asking the same question.