Complex sentence: Pavillion 1, the largest (21.3 m²) which was opened in 2002, is sometimes used as an indoor concert venue as well and can fit up to 6,000 people.
Split into simpler sentences: Pavillion 1, which was opened in 2002, is the largest one (21.3 m²). It is sometimes used as an indoor concert venue as well and can fit up to 6,000 people.