More than 40% of a historic Belfast courthouse has been destroyed in a blaze, the fire service has said.
The large fire at the disused Crumlin Road courthouse in north Belfast was started deliberately.
Most of the damage was restricted to the rear of the listed building, which a developer intends turn into a new hotel for the city.
The fire broke out on Thursday afternoon and caused traffic disruption in the area.
Rita Harkin of the Ulster Architectural Heritage Society said the Grade B listed building was "one of Belfast's key architectural jewels".
"I'm hoping that the interior is still intact," she said.
"It's one of the architectural set-pieces of Belfast and one of Lanyon's most celebrated works.
In pictures: Courthouse fire
"It's unthinkable that this should happen to a landmark of this calibre, especially on a key route like this which is so bereft of any other historic buildings."
The courthouse, which was the venue for hundreds of paramilitary trials, closed in June 1998.
An underground tunnel links one of the docks to a former jail on the opposite side of the road.
The original architect of the Grade B listed building was Sir Charles Lanyon, who was also involved in the construction of some of Belfast's landmark buildings including City Hall, Custom House, Belfast Castle and Queen's University.