Simplify the following text for a Grade 9 native English-speaking person.
Original: Chepstow is most notable for its castle , the oldest surviving stone castle in Britain , and for Chepstow Racecourse which hosts the Welsh Grand National .
Simplified: Chepstow is famous for its castle , the oldest stone castle still standing in Britain , and for Chepstow Racecourse which is home to the Welsh Grand National .