Complex sentence: In 1968, the stadium underwent a major expansion and reopened on May 26,1968 with an increased seating capacity of about 22,000 seats, making it the biggest stadium in Hungary outside of Budapest.
Split into simpler sentences: In 1968, the stadium underwent a major expansion, and reopened on May 26,1968 with an increased seating capacity of about 22,000 seats. At this time, it was the biggest stadium in Hungary outside of Budapest.