Tourists could be charged to enter a Grade I listed estate which has been used as a deer park, military base and hospital.
Cirencester Park is a "nationally important historic landscape", according to the Bathurst family, which has run the estate since 1695.
It wants to install three electronic gates with card readers so tourists can be charged a "modest" fee for access.
A planning application has been lodged with Cotswold District Council.
It is for changes to the park's Cecily Gate, Windsor Walk Gate and another wooden gate at The Barton.
The estate said local residents would retain free access, and it wants to use the fees to sustain the park for future generations by installing new facilities, including a visitor centre and toilets.
Lady Bathurst said a rise in footfall had caused "extensive" wear and tear to the grounds.
The district council has had a number of objections to the proposal, including comments over how free access would remain for Cirencester residents, which they have had since the 17th Century.
In a Facebook post, Lady Bathurst urged people "not to be alarmed" over the "incredibly difficult" decision and said the application was a "first step in a very long process".
"Since 1695, when the Bathurst family first came to Cirencester, the estate has always been available to the community free of charge," she said.
"This will continue. I'm unable to emphasise this enough - for the people of Cirencester, it will always be there for you."
She said a planned Friends of Cirencester Park initiative would allow people to pay a membership fee for extended access and other privileges.