Complex sentence: The park contains the Sapporo Concert Hall, also kown as Kitara, opened on 1997, is the biggest concert hall in Hokkaido, which houses a large main hall, small chamber music hall, and rehearsal rooms.
Split into simpler sentences: The park contains the Sapporo Concert Hall, also known as "Kitara". Opened on 1997, it is the largest concert hall in Hokkaido, and houses a large main hall, small chamber music hall, and rehearsal rooms.