Preston Park, Brighton
Little known and very quiet is Preston Manor an old Manor House at the northern end of Preston Park. It is owned by the council and open to the public, furnished as it was in Edwardian times. I think it should be better known and is certainly worth a visit.
Next to it is a lovely redundant medieval church with wall paintings, including one of the murder of St Thomas Becket. The church is locked but you can borrow the key close by.