Simplify the following text for a Grade 10 native English-speaking person.
Original: He rose to international prominence as conductor of the City of Birmingham Symphony Orchestra and since 2002 has been principal conductor of the Berlin Philharmonic ( BPO ) .
Simplified: He became internationally famous as the conductor of the City of Birmingham Symphony Orchestra which he made into a world-class orchestra . Since 1999 he has been the conductor of the Berlin Philharmonic .