4. Before Renovations, Parts of Federal Hall Were Suspended in Air
The constant jostling from passing cars and subways below led to structural problems for the Federal Hall Memorial, and over the years, cracks began appearing in its masonry. These problems were made exponentially worse by September 11, 2001, when the cracks widened massively. The National Parks Service brought in Langan Engineering and Environmental Services, who penetrated the ground and discovered that in some areas, there was two feet of empty space between the building and the ground. Parts of the building were literally suspended in air.
To solve this problem, a $16 million renovation effort began, involving 60-foot steel pilings driven into the earth in order to inject liquidized concrete into pre-drilled cavities.
Today, the Federal Hall Memorial has a stronger foundation than ever.