The top London law firm relocating to Belfast later this year is to move into part of the city's landmark Obel tower in the biggest commercial letting of 2011.
'Magic Circle' company Allen & Overy will occupy all of the available office accommodation at the 28-storey Donegall Quay skyscraper.
The hundreds of employees coming to Northern Ireland will be given the choice to move into some of the 282 apartments in the same building.
The iconic £60m tower includes 45,000 sq ft with on site basement car parking.
The international firm picked Belfast out of 20 possible worldwide locations and has now chosen Ireland's tallest building as its new home.
The new office, expected to be open by early autumn, will provide a legal services centre and support services, including IT, HR, finance and library. Initially, approximately 200 staff will be accommodated at Obel, which is expected to rise to 400 by 2014.
Invest NI has backed Allen & Overy's investment with assistance of £2.5m.
Launched into the market in 2009, this is the first commercial letting in the Obel for the landlords Karl Properties.
It is understood that originally the smaller building next to the tower was to house a hotel but those plans fell through.
Confirming Allen -amp; Overy's move after months of speculation, Aran Blackbourne, director of Karl Group added that a £2.5m fit-out contract through sister company Blackbourne Integrated M-amp;E has also been agreed, securing more than 50 jobs during a 16-week construction programme starting after Easter.
Additionally, a coffee shop will be in operation at the Obel by the summer and an amenity space is also being developed next to the structure by the Department of Social Development, marking a further boost for a previously neglected area of the city.
Further retail and food tenants could be attracted to the surrounding area by the move, further boosting the local economy.
"Even with the economic downturn, we are most encouraged with the uptake both on a commercial and residential front," said Mr Blackbourne.
"Residential sale completions are progressing on a weekly basis and the letting arm of Karl Group, Obel Living, has made a positive impact on the rental marketplace."
Osborne King and Myles Danker represented the landlord, Karl Properties and CBRE Belfast represented the tenant.
Gavin Clarke of letting agent, Osborne King said that Allen -amp; Overy's commitment at Obel demonstrates that Belfast is seen as an attractive location for international firms despite the tough economic climate.
"We understand Allen & Overy had been considering other worldwide cities for their requirement and clearly the quality of accommodation offered at Obel coupled with Northern Ireland's appeal in terms of highly educated workforce and government agency incentives has resulted in this significant inward occupational coup for Belfast.
In 2009 the Obel complex was selected by Constructing Excellence in Northern Ireland as a "demonstration of design quality using modern methods of construction".
The 'Magic Circle' describes the top five London-based law firms, of which Allen & Overy is one.
Last year marked the 80th anniversary of the firm, and nearly 60% of its revenues are now earned outside the UK and two-thirds of its work is cross-border.
2010 also saw Allen & Overy become the first of the global elite of law firms to open offices in Australia and Indonesia.