Here are just 11 of those buildings, which date back to the 11th century.
1. Historic buildings in Sussex
Some of Sussex's most important historic buildings Photo: National World
2. Alfriston Clergy House
Alfriston Clergy House, an early 15th-century Wealden hall-house near Polegate, is the first building saved forever for the nation by the National Trust. Photo: National Trust Images / James Dobson
3. Arundel Castle
Arundel Castle was built in 1067 by by Roger de Montgomery, Earl of Arundel, and many of the original features, such as the Norman Keep, medieval Gatehouse and Barbican survive. Photo: S Robards SR2204251
4. Bateman's
Bateman's is a Jacobean house that was the home of Rudyard Kipling. It has an 18th-century working watermill that was much loved by the author. Photo: National Trust