Visitors to the grounds of the 16th-century house spotted film crews believed to be preparing the set for upcoming superhero movie The Flash, which stars Ben Affleck, Ezra Miller, Michael Keaton and Kiersey Clemons.
The Tudor mansion has been used for a number of TV shows and films in the past, including Pride and Prejudice, Bleak House and The Crown.
A spokesperson for Burghley House didn't confirm the presence of the film crews, but confirmed that reopening next month is happening as planned.
They said: "The House, as well as the Orangery Restaurant, will reopen as planned on Wednesday May 19. The Park and Gardens are still open daily as usual."