As there are few visible changes on the facade, this week’s photos focus on the reinforced concrete at the base of the tower. With much media fanfare, the NYPD opposed initial designs for security reasons. The resulting redesign introduced a fortress-like base and core, which is now visible from the street level. Eventually, the concrete will be shielded behind a metallic scrim, not unlike the one seen next door on Seven World Trade. For now though, pedestrians can glimpse the exposed base to get an idea of the tower’s extraordinary strength.