Police and fire investigators are trying to find out what caused a blaze that extensively damaged the historic homestead 'Hanworth House' at East Brisbane.
Emergency services were called to the heritage-listed property on Lytton Road in the city's eastern suburbs just after midnight (AEST).
Around half the home was destroyed in the blaze.
The 15-bedroom home was built in 1864 and was undergoing extensive renovations.
Queensland Fire and Rescue Service (QFRS) Superintendent Noel Harbottle says 30 firefighters took several hours to contain the blaze.
"It looks like there's around about 50 per cent of the building destroyed - while 50 per cent has been destroyed, I think it is savable," he said.
"We had timber ceilings, a very steep roof and very hard to penetrate.
"The crews used foam to access the roof space but due to the inaccessibility, we needed lots of crews in breathing apparatus.
"We had to rotate those crews so we used around about 30 firefighters and eight pumps."
Police Inspector Steve Apps says no-one was inside and the cause is being investigated.
"The fire will be treated as suspicious until can be proved otherwise," he said.
"A range of scientific officers and scenes of crime officers will attend."