Heritage attractions in Lincolnshire could be responsible for their own finances after councillors approved plans to look at how the service is funded.
The county council wants attractions to generate their own income and reinvest it, rather than relying on a budget from the authority.
Councillor Nick Worth said it would lead to more innovation.
Opponents said the plans could “seriously damage” the service.
Seven sites, including Lincoln Castle and Gainsborough Old Hall, currently receive subsidies from the Conservative-led county council.
Mr Worth, executive member for culture and heritage, said greater autonomy would benefit both parties.
“The council’s budget position is not going to improve. We’ve got an estimated budget shortfall of £74m over the next three years, on top of the £145m we’ve cut from the budget since 2010,” he said.
“By giving the heritage service a target to fund itself, we’re saving the taxpayer money and keeping the attractions open.”
Currently, money made by the attractions goes back into council coffers, with heritage receiving an annual budget of about £2m.
The new model will mean the service keeps everything it makes in order to fund its activities, the authority said.
However, Marianne Overton, leader of the Independent group on the county council, said: “It is so important to bring heritage to life, but I’m not sure contracting it all out for less money will be the answer.”
Lincolnshire County Council said a full consultation would take place before any final decisions were made.