For 4 years up until September 10, 2001, I often took the N/R subway to work, getting on at 8th Street and getting off at Cortlandt Street, where passengers were disgorged into the huge underground mall below the World Trade Center. I would track past hundreds of commuters, a J.Crew, a Gap, a Sephora; perhaps I’d get a cafe latte from New World Coffee, at the North-east base of the North tower, before heading though its entrance hall on my way to the pedestrian bridge that led to the World Financial Center.

Soon after Sept 11, 2001, the N/R train resumed its service, but without stopping at Cortlandt Street. The first few days, passengers would look up from their doings and stare quietly out the carriage windows at the wooden support struts that had been hastily built. In orange spray paint on the walls, “DO NOT STOP,” conductors were told. After a few months, as the salvage efforts on Ground Zero progressed, the station was cleaned up, and the struts disappeared. People no longer looked up or grew quiet as we passed the station.

Yesterday, for the first time, out of the corner of my eye, I noticed a bright spot where the mall was. Today, I confirmed it: the exit that used to take me to the mall has been opened by workers, and it leads to bright daylight.

I’ve grappled with the idea that in my head, the mental map I’ve built up from years of walking through the World Trade Center still exists, even though the place does not. Until today, subconsciously, the mall still existed behind those boarded-up doors.

In the same way, being kept away from the actual site of the disaster protected me from having to update this map, but as of yesterday, they let you walk all along the southern perimeter of Ground Zero, with an unobstructed view of the site, much like any construction site. I walked by there. You can clearly see the rebuilding of the 1/9 subway line, as well as many partly demolished subterranean levels. I’d seen some of this before from our office’s window at Falkor LLC, but being right next to it, on the ground, makes it all a lot more immediate. Go and have a look if you haven’t been recently.