In the late 1980s, the New York Public Library was faced with a space shortage: the research collections were getting too big for the main building on Fifth Avenue. Discussions were had about moving the stacks to a warehouse in New Jersey, which would have meant materials moving back and forth across the river constantly, slowing down researchers who would now be forced to request items in advance.
Instead, the library decided to build huge underground stacks underneath neighboring Bryant Park, which was currently undergoing renovations of its own. A two-story facility was constructed, with one level housing 84 miles of stacks, capable of holding 3.2 million books. The Milstein Stacks were later expanded to the second level in 2016, adding space for an additional 2.5 million materials.
While the stacks are accessible from the main library building, with patrons requesting materials and staff sending them up via the internal conveyor system, the vast underground nature of the facility means that in case of emergency, there has to be another way for employees to leave the Milstein Stacks.
Thus a large emergency hatch was built at the west end of the park, on the edge of the Great Lawn. But since a giant metal door would distract from the French garden layout of Bryant Park, the hatch was partially concealed by a large plaque listing the park’s major benefactors, like former mayors Ed Koch and David Dinkins.