3. Column Remnants inside the PATH Station
The engineering firm Skanksa built both the original World Trade Center and the new Transportation Hub (aka Oculus), designed by Santiago Calatrava. In the Oculus, which services the PATH train, the 1 subway line (with walkways to the Fulton Street subway lines), there was a deliberate move to remember what happened on 9/11.
To that end, the design has made visible the sections of the original steel framework and concrete foundation of the Twin Towers. You can see these sections under glass on the platform of the PATH station.