Complex sentence: Livonia Mall remained largely unchanged until the mid- 1980s, when the formerly open-air concourses were enclosed; also in 1985, a new wing ending in a Mervyn's department store was added.
Split into simpler sentences: Livonia Mall remained largely unchanged until the mid- 1980s, when the formerly open-air concourses were enclosed. Also in 1985, a new wing ending in a Mervyn's department store was added.