Bulldozers have begun tearing down a prominent art deco building, once a motor showroom, in Hove.
Historians and conservationists had hoped the Thirties structure in Kingsway could be saved but were unable to persuade English Heritage to have the building listed.
Now owner Caffyns has begun work to demolish it.
It is not clear what the firm plans to do with the site. Brighton and Hove City Council says it has received no planning applications for it.
Historian and conservationist Sylvia Adams is hoping the owners might agree to keep at least part of it as it is.
Miss Adams, who is a member of various civic and archaeological societies in Brighton and Hove, said: "Is it really too late to save this building?
"It is a piece of our history. It is on the entry to Hove and it has got something special about it. Caffyns should be shaken up and be shown it is wrong to do what it is doing."
Miss Adams said she was shocked to see hoardings placed around the building as work began to tear it down.
She said she remembered the garage as a child at the start of the Second World War, when it was used by the army to repair military vehicles. She believes it has important historical value for the area.
The building dates back to 1928 and was designed by EJ Love for the motor trade.
It was enlarged ten years later. For many years, there was a car showroom on the site but it closed two years ago and the building continued to be used as a parts centre.
A spokeswoman for Brighton and Hove City Council said: "It is on the council's list of buildings of local interest.
"From time to time this list gets sent to English Heritage to see if any of the buildings should be listed. The last time it was sent was in the early Nineties and English Heritage did not consider it to be of a good enough quality then and it is in a worse condition now.
"Any new building will require planning permission and as this is a landmark site a new building would have to be of a good quality and design."
No one from Caffyns was available for comment.
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