When the Titanic hit the iceberg on an April evening in 1912, the fortunes of the city in which it was built began to sink with it.
The Titanic was the biggest man-made moving object on Earth, a triumph of Edwardian technology, the space shuttle of its time. Such was the shock to Belfast's psyche when it sank that for decades you could be sacked from the shipyards for mentioning the word "Titanic."
Belfast's precipitous decline from one of the great thrusting industrial cities of the world into a century of Troubles and disappointment can almost be traced to the moment of the sinking.
So it is hardly surprising that an artist's plan to tow an iceberg from the Arctic to Belfast is dredging up ghosts that some in the city would rather not stir.
For Rita Duffy, Northern Ireland's foremost artist, mooring an iceberg off Belfast and allowing it to melt is about "thawing" a place locked in a political and emotional deep freeze where divisions are firmer than ever.
"A huge big mountain of ice seems to be the most eloquent way of describing where we are. There is a certain type of madness in Northern Ireland society, a denial of what has happened to us. Maybe it's time to come out of denial and confront what has sunk us," she said.
Duffy, whose father was one of the few Roman Catholics allowed to work in the shipyard, sees the iceberg as a living sculpture which the city will watch melt away.
"The iceberg is a figure of fear and I hope its melting will have a cathartic effect. Ice is the alchemic opposite of the fire of hatred and sectarianism, mistrust and dislike, that has burned here," she said.
But most importantly, Duffy says, it is about Belfast daring to think big again.
She hopes to tow an iceberg from Greenland down the old Viking route.
For her, that journey, mirroring the migration of some of the peoples who settled Northern Ireland, will be as important as the weeks and months it sits off Belfast. It will be lit up as it comes down the Western Isles of Scotland, which shared a common Gaelic language with Ulster and from where Protestant planters migrated in the 17th century.
Duffy has the support of Belfast's mayor and some leading academics and business people. Northern Ireland's Pulitzer prize-winning poet Paul Muldoon has joined Thaw, the company Duffy has founded to run the project.
She has been to Newfoundland to inspect icebergs, although it could be three years before the money is raised and technical hurdles overcome.
The writer Polly Devlin, opening Duffy's exhibition of film and painting, "Contemplating an Iceberg," at the Ulster Museum this week, said: "Titanic was a Belfast symbol. It carried this amazing freight of hopes and fears and hubris. If an iceberg was to come into Belfast Lough, the vast enemy coming back and being wedged there, it would be a wonderful closure."
But Una Reilly, co-founder of the Belfast Titanic Society, said it was too soon after the tragedy for this kind of art.
"I can understand why Rita wants to develop the symbolism of an iceberg," Reilly said. "But to bring the cause of the disaster into Belfast is not the message Belfast wants to send out to the rest of the world in relation to the Titanic."
Belfast is reinventing itself and reclaiming the word "Titanic." There are plans for a ?1 billion (US$1.87 billion) redevelopment of the docks, to be called the Titanic Quarter.