Documents dating back to the Middle Ages stored in archives at Arundel Castle are being put on display.
The castle has renovated the Waiting Room for the display
The permanent exhibition is being set up in the Waiting Room at the West Sussex castle, which overlooks the River Arun and the south coast.
The room where visitors waited before visiting the duke will now be used for exhibiting the documents, portraits, pictures and illustrations.
A spokesman said the private collection was "one of the finest in the country".
She said the Waiting Room, once used as a store room, had been specially restored for the exhibition.
The oak parquet floor has been rewaxed, new lighting installed, the stonework cleaned and the walls repainted.
The castle is highlighting the connections of the building and the family with the sea this year, to mark the bicentenary year of the Battle of Trafalgar.
The 15th Duke of Norfolk's grandfather, Lord Lyons, was an Admiral and Commander of the Mediterranean Fleet during the Crimean War.
His godfather was one of Nelson's officers at Trafalgar, and some of the items now going on display include Nelson's orders in the years leading up to the event.