The Department of Culture, Media and Sport (DCMS) has listed the controversial Regent Palace Hotel in London.
A row broke out last month between conservation groups and the developer, Crown Estate - with its architect Allies and Morrison - over whether the building should be saved.
The Twentieth Century Society and SAVE Britain's Heritage have both lobbied the government over the importance of the 1915 building and its Art Deco bars and restaurants by Oliver Bernard.
And now the building's potential demolition is facing a major setback following the DCMS's decision to register it as Grade II.
SAVE director Adam Wilkinson said: 'SAVE is delighted to learn that this handsome hotel is to get the protection it deserves.
This sends out the strongest possible signal to Crown Estate that demolition is not an option.
We look forward to seeing an application for its careful refurbishment.
'It has taken almost a year for the DCMS to list the Regent Palace Hotel, but we are pleased that they have reached the right decision, ' he added.