About 250 people have taken part in a rally in the centre of Londonderry to protest against Wednesday night's bomb attack on the City of Culture offices.
Church leaders, politicians, and representatives from the arts sector were among the crowd who gathered in the city on Thursday afternoon.
Police said the bomb could easily have killed. A senior police officer said the attack was "crazy".
It is the second time Derry's 2013 City of Culture offices have been bombed.
Dissidents republicans are being blamed for the bomb which went off just before 23:00 BST on Wednesday. No-one was injured but buildings were damaged.
Crude and clandestine
Chief Superintendent Stephen Martin said a warning was given to a community representative at about 21:45 BST.
About an hour later, just as police had cleared the area, the device exploded. An Army bomb squad was still on its way to the scene.
The City of Culture offices, responsible for organising Derry's year in the spotlight, are located in the heart of the city and many people were socialising in pubs nearby.
A recognised codeword was used during the bomb warning and security sources believe dissident republicans were responsible for the attack.
Chief Superintendent Martin said the door frame and shutters of the City of Culture office was badly damaged while windows in nearby buildings were smashed.
He added that he was certain anyone passing the bomb when it exploded would have been killed.
"They are not made by sophisticated manufacturing processes. They are made in a clandestine way, in a crude way," he said.
"People may put a timer on it but mistakes happen and it's only a matter of time before a mistake does happen and these people take a life."
Witnesses said it was a large blast which left smoke billowing out of the building.
Resident Karl Hamilton said the force shook his house across the river and woke most of his children up.
"I had just finished putting my children in bed about 20 minutes beforehand when we suddenly felt the house shake," he told the BBC.
"Windows and doors rattled, accompanied by an extremely loud bang.
"Initially I thought it was fireworks before realising it was the bomb. The younger children still think it was a firework - that way they won't be worried.
"The older ones, however, are immediately broadcasting the news on Facebook."
He added: "I really don't understand why the perpetrators of such action actually think they represent the vast majority of people in our city when most of us just want a simple life."
In a statement, the Department of Culture said: "The reaction of the city to the news this morning clearly demonstrates the huge community support that is behind the City of Culture programme."
It said it would see the city "host a year-long celebration of culture, opening its doors to visitors from across the world.
"We wish the city well as it continues to plan for a successful year as UK City of Culture in 2013."
Foyle MP Mark Durkan said: "Thankfully no-one has been injured but those graces are no thanks to those who are behind this attack.
"They are out to destroy and they don't care if they injure or kill when they are at it.
"Derry is a city with many challenges and with many difficulties. But the City of Culture is one of the opportunities we have."
He added: "This callous and dangerous act flies in the face of the efforts made by so many people to improve life here."
East Londonderry MP Gregory Campbell also condemned the bombing.
"These people are merely trying to do what others have tried for 30 years before them, and failed," Mr Campbell said.
"They simply do not get the picture, it doesn't matter how many times they try they will repeatedly fail as their predecessors in the Provisional IRA did before them."
The Chief Commissioner of the Northern Ireland Human Rights Commission also condemned the attack. Professor Michael O' Flaherty who was in the city on Wednesday said the bomb had breached the human rights of those living in Derry. He said residents would stand up to those who had carried out the attack.