Letters between Elizabeth I and Robert Dudley form part of a new display which has just gone on show to mark the end of a £2.5m investment project.
The exhibition marks the end of the castle's revamp
The Gatehouse at Kenilworth Castle, once Dudley's home, in Warwickshire has been restored to look how it would have when it was last used as a home.
The letters, written almost 500 years ago, used symbols similar to modern text speak, experts said.
The symbols @@ have been used as substitutes for pet names.
Married Robert Dudley, the Earl of Leicester, is thought to have been a favourite of the Queen.
The last two hand-written letters he wrote to her before he died are among the exhibition which also features their portraits and tapestry work.