A nineteen-year-old man has been arrested on suspicion of an arson attack at the former North Wales Hospital in Denbigh.
North Wales Police made the announcement yesterday evening. The man has since been released on bail.
Firefighters spent five hours getting the blaze under control last Monday with crews returning on Tuesday after the an ember set part of the building alight.
The historic former psychiatric hospital and it's Grade II* listed main building has been at the centre of a long running dispute over it's condition with Denbighshire County Council poised to take over the building and hand it to the Princes Regeneration Trust for development aimed at securing it's future.
The North Wales Hospital was designed by architect Thomas Fulljames in 1844 and completed in 1848. At its maximum capacity it could house up to 200 people with psychiatric illness.