Fire investigators have said the cause of a blaze that destroyed what was described as England's oldest hotel will remain a mystery.
In its report into the fire at the Royal Clarence Hotel, the fire service said evidence of how it started was lost when the building next door - where the fire started - collapsed.
No guests were injured in the blaze that broke out in Exeter last October.
The report said the operation to put the fire out cost £250,000.
The report said crews "were faced with a wall of raging fire" on 28 October 2016.
It added that the fire was made worse by many hidden voids and ventilation pipes which acted like chimneys spreading the blaze.
- Total pumping appliances used (includes repeat visits by the same appliance): 231
- Total number of firefighters that attended: 1,186
- Fire service vehicles that attended: 135
- Aerial ladder platforms that attended: Five
- Maximum number of firefighters on scene at the same time: 207
- Cost: £250,000
The fire service identified a number of voids in an inspection in 2015, but they were unable to identify the specific location without causing significant damage.
They stemmed from adaptations to the building made many years ago when there was "very little in the way of statutory regulations", the report added.
The report said that fire regulations could not be enforced retrospectively, "meaning that any existing buildings do not necessarily need to be adapted or, changed in line with the implementation of new regulations as new builds would".
Historian Dr Todd Gray said the Royal Clarence, which overlooks Exeter Cathedral, was the first venue in England to call itself a hotel.
The hotel was built in 1769, and the landlord in its early days was a Frenchman, Pierre Berlon, who is said to have been the first to apply the word "hotel" to an inn in England.
Owners Brownsword have said a new hotel will be built on the site with the same facade as its predecessor.