Businesses in central Belfast are assessing the damage caused by the city's worst fire in years, writes Dan Keenan, Northern News Editor.
A police inquiry begins today and arson has not been ruled out. The Fire Service regards the outbreak as suspicious.
A stretch of Royal Avenue remains part-cordoned off and traffic restrictions are expected to last until tomorrow.
Belfast Chamber of Commerce will hold an emergency meeting to discuss the fire's impact.
The Victorian building was damaged by fire and water, stock at a landmark branch of Waterstone's bookshop was destroyed, and the blaze also damaged neighbouring Goldsmith's jewellery shop.
It is understood the jobs of 25 staff at Waterstone's are not under immediate threat despite the loss of stock on the eve of the Christmas shopping season.
Office accommodation on the four floors above the street-level retail premises was the worst affected. Legal practices and the Northern Ireland bureau of the Press Association were hit by the loss of files, computers and other equipment. Journalists at PA have moved to temporary accommodation at the Belfast Telegraph.
Some 100 firefighters from three counties were involved at the peak of the fire. It broke out at about 2 a.m. yesterday and was still being attended in the late afternoon.
The blaze is thought to have started in the upper floors towards the back of the building overlooking Berry Street.
At one stage it was feared the large Castle Court shopping complex beside the burning building was under threat.
A listed building next door, occupied by the Reform Club, was also spared major damage. Royal Avenue was closed throughout most of yesterday causing significant traffic disruption.
It is the second major fire in Belfast city centre this year.
The nearby North Street Arcade was extensively damaged in a blaze last April.
An assistant senior divisional commander of the Fire Service, Mr Chris Kerr, said: "This is a major incident and one of the largest fires in Belfast for many years."
He told the BBC: "Thankfully, we have managed to contain this fire without any further risk to firefighters. About 25 per cent of the second floor and 50 per cent of the third floor have been damaged, but sadly all of the fourth floor and roof structure have been destroyed."
Engineers surveyed the damage and early reports have raised hopes that the building can be restored.
The Ulster Architectural Heritage Society said retention of the building was essential to the city centre. Ms Rita Harkin said: "That whole group of buildings forms such an important part of Victorian planning. It would be an enormous loss and every effort has to be made to maintain as much of the fabric as possible."