A large section of the Grange Hotel is to be demolished after the building was gutted in a fire six weeks ago.
Alex Baldwin, conservation adviser for the Victorian Society, said: "The fire at the Grange Hotel was a tragedy for Rhyl on many levels. We urge Denbighshire County Council to salvage everything possible from this sad event by ensuring that the surviving villa is properly supported and that whatever is built on the site complements its Tudor Gothic character.
"It's the very least a nationally significant building like the Grange Hotel deserves."
The Grade-two listed hotel was built in the 1840s as a pair of private villas, known as Morannedd and Boddonna and was a hotel until its closure in 2007.
A spokeswoman for Denbighshire County Council said: "The loss adjuster has just completed his review of the site and is preparing his report. At the present time, the eastern section is seen as being 'saveable' and the western section not - although the agents must justify any significant demolition as they are listed buildings. There is no presumption that anything will be demolished at this point in time."
Mark Isherwood, North Wales AM and Shadow Minister for Housing, said: "Much of historic Rhyl has disappeared over the last fifty years, including its famed Pavilion Theatre and Pier. It would be hugely disheartening if another piece of our collective heritage was lost."