A national campaign group is urging the district council to take action to save Malvern's Grade II listed Tudor Hotel.
The Victorian Society, which fights to preserve Victorian and Edwardian architecture, said it was calling on the Malvern Hills District Council to serve an Urgent Works Notice on the owner of the Victorian building.
The Tudor Hotel, on Wells Road, has been unoccupied for several years and the society claims it is is neither properly secured nor fully watertight.
Campaigners said the building was dangerously exposed and vulnerable to the worst of the winter weather.
In 2006 permission was granted to convert the hotel into 14 luxury apartments but work didn't start and the society believes the building has been neglected. The owners recently applied to the council to extend the planning permission.
Kristian Kaminski, conservation adviser of the Victorian Society, said: "If something isn't done soon to secure the site then there is a real danger that the building could be irreparably damaged.
"The Tudor Hotel is an attractive and important part of Malvern's history and must not be left to rot."
The Victorian Society believes the hotel is a wonderful example of an early Victorian purpose-built water cure centre. It was commissioned in 1852 by Dr James Gully, who played a principal part in establishing Malvern as an important spa town, and was designed by architect, Samuel Saunders Teulon.
But the society has warned that the former hospital's gothic facade, spiral staircases and turrets won't survive for future generations unless the fabric of the building is maintained.
Section 54 of the Planning (Listed Building and Conservation Areas) Act 1990 enables local authorities to execute works which appear to them to be urgently necessary for the preservation of a listed building.
The Victorian Society is a national charity campaigning for the Victorian and Edwardian historic environment. It fights to preserve important Victorian and Edwardian buildings and landscapes so that they can be enjoyed by this and future generations.
For more information, visit www.victoriansociety.org.uk.