A Devon council is to appeal against new Grade II listed status awarded to a 1960s office block which it is considering knocking down.
English Heritage said the centre had "very fine internal decorations"
Plymouth City Council wants to move out of the 14-storey Civic Centre which it says is "long past its sell-by date".
The government awarded the status after a request by "more than one person" and advice from English Heritage.
The council has 28 days to appeal against the listing. MP Alison Seabeck has asked for the status to be revoked.
English Heritage says the Civic Centre, opened by the Queen in 1962, is a "very important post war building and is an iconic feature in the centre of Plymouth".
It recommended the listing on the basis that it was a complete set of civic buildings and had an "unusual richness of art work" and "very fine internal decoration".
The council opposed the listing when they heard it was being considered several months ago.
This month, Plymouth City Council put forward a firm to develop the Civic Centre site and a new home for its 1,000 staff.
The council plans to lodge an appeal for its demolition
A spokesman said: "The Civic Centre is long past its sell-by date.
"If we are refused permission to demolish the building there are serious financial implications for the council as the Civic Centre is in need of major work to fix structural problems."
The council is now taking legal advice and considering lodging a new planning application for demolition of a listed building.
Mrs Seabeck told the Commons on Monday the listing was "disastrous" and called for it to be reconsidered.
Government minister David Lammy said he would talk to his officials but pointed out that listed buildings could still be updated.
A Grade II listing recognises a site's special interest and warrants every effort to preserve it.