Complex sentence: Oxford Properties took over the building in 1998, it released plans to replace the Concourse Building with a 40-story glass-inspired, 720,000 square foot tower that would incorporate two of the original walls of the Concourse Building.
Split into simpler sentences: Oxford Properties took over the building in 1998 and released plans to replace the Concourse Building with a 40-story, 720,000 square foot glass tower. The proposed building would incorporate two of the original walls of the Concourse Building.