Woburn Abbey in Bedfordshire is due to start its biggest refurbishment since it opened to the public in 1955.
If the work gets planning permission, the Abbey will close to visitors in September 2019 for 18 months.
The plan is to conserve artworks and update the venue as a visitor attraction, including transforming the Grotto into an entrance as it would have been in the 1600s.
"My grandfather opened the house over 50 years ago, and we've done bit and pieces," the Duke of Bedford, Andrew Bedford, told ITV News Anglia.
"We now want to change the visitor route and do it in a more historical fashion. We want to take people round from the beginnings of the Abbey to the present day.
"We're also going to put in disabled access, which will be a great thing. We're opening the whole place up and refreshing it."