Complex sentence: Marks and Spencer's and the adjacent Longridge House were condemned as unsafe within days (and would be demolished), the frontage of the Arndale on Corporation Street and the footbridge was also structurally damaged, and in all 1200 properties on 43 streets were affected.
Split into simpler sentences: Marks and Spencer's and the adjacent Longridge House were condemned as unsafe within days, and would be demolished. The frontage of the Arndale on Corporation Street and the footbridge were also structurally damaged, and in all 1200 properties on 43 streets were affected.