A Grade II-listed former farm house in Swansea should be opened up to the public rather than being "lost for private housing", the leader of the council's opposition group has said.
Labour leaders want to transform the Home Farm council depot in Singleton Park into a 42-home development, including some affordable housing.
Lib Dem Chris Holley accused them of "riding roughshod" over public opinion.
Labour insisted that none of the surrounding parkland would be lost.
Singleton Park was once part of the estate of the Vivian family, owners of the city's former copperworks, who sold it to the local authority in 1919.
The farmhouse dates back to the 1830s, and has been used for office space in the council depot.
Council bosses plan to keep the ownership of the site, hoping to generate capital and revenue payments from a developer.
Liberal Democrat councillors told the Local Democracy Reporting Service they felt consultation over the housing plan had been "lacking", with "major concerns" among local residents about the effect on the surrounding parkland.
Cheryl Philpott, who represents the local ward of Sketty, said: "Large parts of the park are already being used by Singleton Hospital and Swansea University, and the council has already agreed that the university have control of the Swiss Cottage and more areas of the park."
Group leader Chris Holley said the Lib Dems felt that "early intervention" was "essential to make sure that all of Swansea's largest park remains in public ownership".
He accused Labour of "riding roughshod over public opinion and closing its mind to innovative solutions" to the future use of Home Farm which could open it to the public and generate income.
Swansea Council leader Rob Stewart said: "The Lib Dems should support the restoration of our historic buildings.
"Redevelopment of the council compound at Home Farm will return this site to public use while avoiding any impact on Singleton Park."