Glasgow City Council has confirmed that the buildings hit by a fire on Sauchiehall Street will be demolished.
A major blaze ripped through the block, which housed businesses including Victoria's nightclub, on Thursday.
The council has now said the buildings are unsafe and will have to be pulled down by their owners.
The fire was one of the biggest faced by Scotland's fire service since it was amalgamated nearly five years ago.
The fire took hold in the roof of the building at about 08:20 on Thursday.
At the height of the blaze, more than 120 firefighters and 20 fire engines were mobilised to the city centre.
The buildings at 92-96 and 98-106 Sauchiehall Street will now be demolished.
Glasgow City Council estimates that some of the roads and footpaths in the area could be shut for two months while the work takes place.
A spokesman said: "The police and fire service are still technically in charge of the site, although this is in a transition stage with the council's building standards team likely to assume control of the site late today or tomorrow.
"An exclusion zone has been erected around the site of the dangerous buildings, which will be demolished as they cannot be saved.
"Roads and pathways around the site will be closed for a considerable time - a likely estimate is two months for some of them - to allow demolition, and more detailed information will be made available as soon as possible throughout the process."
The spokesman added: "We have met with the owners of buildings affected by the fire, and will maintain this dialogue over the period.
"The owners of properties in the buildings to be demolished have met with insurers to discuss the next steps."
On Thursday, thick smoke billowed across the city for much of the day with fears the fire could spread to nearby buildings, including the historic Pavilion Theatre.
It is thought the theatre could remain shut for several weeks due to smoke damage.
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