The fate of a historic north Derbyshire castle is uncertain after people living nearby said they want to buy the site from a property developer.
The castle grounds used to house a wildlife park
Protesters believe it is the only way to stop housing being built on the site of Riber Castle near Matlock.
They say plans to build apartments and houses in the grounds will lead to more traffic and pollution.
The developer has already been granted planning permission but the scheme still must go before a public inquiry.
The ruined castle was bought in for £700,000 in 2000 by developer Cross Towers Ventures who won permission to build 35 apartments and 11 houses at the property.
Opponents said the new buildings could quadruple the size of Riber - the nearby hamlet - and that extra lighting and more traffic will destroy the character of the area.
They insist there are numerous sources of funding available - including Heritage lottery cash - but are unable to set up a charitable trust or estimate the amount of money they would need without access to the property.
Bill Clay, from Cross Towers Developers, said: "We are interested in anyone who has a robust solution to save Riber Castle for the long-term future.
"Our door is always open to someone who can come forward with a plans which is justified financially."
The public inquiry into the plans will be held in November.
The castle grounds were used as a wildlife park for many years, but it closed in 2000.