The Grade II-listed Cumberland Lodge will be opening its doors for the first time.
As part of the Heritage Open Days festival, guided tours will take place on September 9 and 10.
The lodge in the heart of Windsor Great Park was built in the 1650s by John Byfield, a member of Oliver Cromwell’s army.
It was granted its current use for educational events and retreats by King George VI and Queen Elizabeth in 1947.
Ed Newell, Cumberland Lodge principal, said: “This place has an amazing history.
“There are so many fascinating stories to tell, from its republican roots to its royal residents.”