Simplify the following text for a Grade 8 native English-speaking person.
Original: The castle has for centuries been one of the most important Renaissance castles in Northern Europe and was added to UNESCO 's World Heritage Sites list on November 30 , 2000 .
Simplified: The castle has for centuries been one of the most important Renaissance castles in Northern Europe . It was added to UNESCO 's World Heritage Sites list on November 30 , 2000 .