17 feet below ground, in a concrete bunker...the (NYPL)...is expanding.

Yes, the NYPL had to reevaluate and re-imagine expansion. The solution is clever, practical, secure and technically smart.

"The Bryant storage space consists of two floors, the first of which was put into use in the late 1980s, while the second floor, dug out but not finished back then, has lain fallow. Now, to accommodate the books long housed in the original 105-year-old stacks, a part of the library whose future is still under discussion, the second floor is being turned into a state-of-the-art storage hub."

Here's the link to the full article in the NY Times.