No-one was hurt in the fire which began in the early hours of Saturday
About 90 firefighters tackled a large fire which engulfed a pub, offices and flats in a town square in Dorset.
It is thought the fire in Wimborne began in a flat above a newsagents and post office, before spreading to two travel agents and the Albion Hotel.
No-one was hurt in the fire, which began at about 0230 BST.
Crews managed to prevent the fire spreading to the nearby Priest House Museum, an historic grade II listed town house.
Phil Allen, who was the incident commander during the height of the blaze, said the roof of the building had almost been destroyed and local authorities would have to determine how safe it was.
It was too structurally unsafe at present to begin an investigation into the cause, he said.
The town's mayor, John Burden, said the High Street and square would be closed for most of Saturday.
He said the fire service believed the fire had begun "in the flat above Martin's the newsagents and post office".
"And of course, being an old building, with old timbers, it just goes beserk."
Former mayor Anthony Oliver said the scene around him was one of "devastation".
He said the fire seemed to have spread from the flat to the Thomas Cook travel agents and Saville Travel, before reaching the Albion Hotel - the oldest coaching house in Wimborne.
He added the post office was the only one in the town.
'No loss of life'
"The most important thing of all is, as far we understand it, no damage to life, no loss of life, no injuries, from what we hear," he said.
Mr Allen said retained fire crews were first on the scene before calling in extra help.
"We utilised our aerial ladder platform, which allowed us to get water on to the fire and prevent it reaching a well-known building, which is the Priest House Museum."
The museum showcases east Dorset life from prehistoric to modern times.
"Luckily, crews worked particularly hard, and with some difficult access, but managed to stop that fire spreading."