3. The New York Public Library has 125 Miles of Book Stacks
If you’ve ever walked into the New York Public Library and wondered, “Where are all the books?” the answer lies beneath your feet. Around 4 million books are stored in subterranean stacks beneath the library building and Bryant Park. The library contains 125 miles of shelving both above and underground, including 88 miles spread throughout the seven stack floors of the Humanities and Social Science Library, and 37 miles in the two-level stack extension under Bryant Park called the Milstein Research Stacks. In addition to the sprawling stacks beneath the New York City site, there are also millions more books stored in an off-site facility in Princeton, New Jersey.
The self-supporting steel stacks as structural elements of the building. The stacks act as buttresses to the floor of Rose Main Reading Room. Snead & Company Iron Works of Jersey City, New Jersey were the contractors for the stacks which are made up, in part, of Carnegie steel.