4. World Trade Center Slurry Wall

9/11 slurry wall

The original slurry wall of the World Trade Center enclosed an enormous basement the size of four city blocks by two city blocks, known as the “bathtub,” that held back the water from the Hudson River. Half of the World Trade Center site exists on landfill over what was originally marshland and water. The basement itself took up 70% of the World Trade Center site, and was surrounded by a 3,500 foot long slurry wall that was three feet thick.

According to George J. Tamaro, one of the engineers who was in charge of the construction of the slurry wall, the wall survived the 9/11 attacks “mostly intact.” In the design of the 9/11 Memorial & Museum, part of the slurry wall became the focal point of Foundation Hall, a 40 to 60 foot high space that also contains the “Last Column,” a 36 foot tall piece of steel signed by first responders, recovery workers and volunteers. The creation of the bathtub of the original World Trade Center resulted in the excavation of 1 million cubic yards of soil and other material, which eventually formed the foundation of Battery Park City, yet another one of the many man-made places in New York City built atop excavation from somewhere else.