Complex sentence: The Preis der Diana is a Group 1 flat horse race in Germany for three-year-old thoroughbred fillies run over a distance of 2,200 metres (approximately 1 mile 3 furlongs) at Düsseldorf Racecourse, Düsseldorf in June.
Split into simpler sentences: The Preis der Diana is a Group 1 flat horse race in Germany for three-year-old thoroughbred fillies. It is run over a distance of 2,200 metres (approximately 1 mile 3 furlongs) at Düsseldorf Racecourse, Düsseldorf in June.