Complex sentence: In the next decade, 300 skyscrapers were erected in the city, including the International Foreign Trade Center, the city's first skyscraper taller than and also the tallest building in mainland China upon its opening in 1985.
Split into simpler sentences: In the next decade, 300 skyscrapers were erected in the city, including the International Foreign Trade Center. It is the city's first skyscraper taller than and was the tallest building in mainland China upon its opening in 1985.