The economic spin-off from Londonderry's City of Culture year could reach £500m, the council's chief executive has claimed.
Sharon O'Connor said the bonanza from the 1.3 million visitors expected to descend on Derry during 2013 would generate global exposure and jobs.
Ms O'Connor said: “The potential is just massive.
“We are estimating £500m.
“The value is across a whole range of things.
“It is not necessarily just all money in tills — it is also about the media value of the exposure that we get and there's no doubt that jobs will be created.”
Capital investment worth £100m has already been pumped into Derry since the City of Culture title was secured in 2009.
The latest cash injection came earlier this year when Stormont Environment Minister Alex Attwood pledged £100,000 to tackle dereliction and remove graffiti.
Officials have also estimated that up to £98m in additional wages and profits could be generated over the next 12 months.
But there are other benefits which are more difficult to put a value on.
The Culture Company, which is organising next year's celebrations, hope that by the end of 2013 Derry will have jumped from 49 to 20 in the league table of top UK cities.
Ms O'Connor also said the educational and social legacy was priceless.
She added: “We are giving our young children an opportunity to see futures for themselves that in other circumstances they might never have been able to imagine.
“Bringing this global exposure to their city shows them that the opportunities for them are unlimited.
“And you can't put a value on that.
“The whole city is very excited.
“Everyone from the taxi drivers through to the people who run businesses.
“Practically everyone in the city is engaged at some level and that's part of why we won the bid.
“And that will be part of why we are confident that we can accrue the economic legacy.”
Derry was recently placed fourth in the Lonely Planet's list of top 10 cities to visit next year.
Ms O'Connor said that people would be pleasantly surprised.
“One of the things that gives us real stand-out and personality is that 40% of the population here is under-25,” she said.
“Practically every kid in the city is involved in a band, they are very quirky and energetic in the way they encounter life,” the chief executive said.
“It is a very interesting place full of surprises for people who have not been here before, especially for people whose image of the place is historic and not one that is contemporary.”
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