Gardaí say it will be tomorrow at the earliest before they are in a position to carry out a technical examination to establish if a fire at a former convent and orphanage was arson.
Firefighters spent several hours earlier today making safe the former Good Shepherd Convent and Magdelene Laundry at Sunday's Well in Cork.
The blaze broke out at the former convent sometime before 7.30am and five units of Cork City Fire Brigade battled to try and save the historic building
Cork City Fire Service Third Officer, Victor Shine said firefighters were confronted by a significant fire when they arrived at the former convent on the northside of Cork city.
"We were met by a substantial section of building, approximately 50 metres of the convent section well alight, from the ground floor up through to the roof," he said.
"The total floor area of the building has collapsed on itself - you're left with the outer perimeter structure of the building - [the] bricks, ceiling and roof have collapsed in."
Supt Con Cadogan of Gurranebraher Garda Station said that gardaí hope to get a technical team into the shell of the building tomorrow to try and establish if the fire was started deliberately.
Supt Cadogan appealed to anyone who may have seen any suspicious activity at the convent or in the general Sunday's Well area to contact them on 021-4946200.
The building had been unoccupied for some time and had no power supply so it was clear a fire was started but whether it was done so deliberately or spread accidentally was unclear.
The Good Shepherd Convent and Magdalene Asylum first opened in 1872 and continued to operate as an orphanage for young girls right up until the late 1970s.
Three of the structures on the site, the convent, the Magdelene home and the orphanage were designed by George Ashlin and were listed as protected structures.
The building, which is adjacent to the tourist attraction of Cork City Gaol, has been unoccupied for over a decade and was previously damaged in a fire in 2003
The eight acre convent site was purchased by UCC in 1995 with the aim of accommodating departments of Social Studies, Adult Education, Music and Law on a new campus.
However the plan, which would have seen some 1,500 students on campus, was abandoned at the design stage when UCC acquired additional lands adjacent to the existing campus.
The property was sold to developer PJ Hegarty who planned to turn it into student accommodation but the project never got off the ground and he later sold it.
It was bought by the Frinailla Group in 2005 for €20million and they obtained planning permission for 200 apartments with two bedroom apartments due to sell for €450,000.
However the Frinailla Group went into receivership in 2010 when Ulster Bank moved in on its assets which were mainly in Cork and KPMG was appointed as a receiver to the company.
Today local Fine Gael Cllr, Joe O'Callaghan said it was an "absolute disgrace" that such a historic building could be allowed to fall into dereliction and then be destroyed in a fire.
