Simplify the following text for a Grade 9 native English-speaking person.
Original: In 1997 the non-metropolitan county ( including unitary Darlington ) , together with that part of the former county of Cleveland north of the River Tees became a ceremonial county . Lord-lieutenants and high sheriffs are appointed to the ceremonial county of Durham .
Simplified: County Durham is a ceremonial county and ( smaller ) unitary district in North East England .