This segment originally aired in October, 2016.

How do you arrange your books? By author? By title? By subject? By colour?

The New York Public Library has a lot of books. Like, a lot of books. And the island of Manhattan isn't such a big place.

So the library has come up with, if you pardon the pun, a novel solution: organizing some four million books by size. Kind of like book Tetris!

It built an underground storage space beneath Bryant Park -- made famous in countless movies and TV shows for its skating area in the winter and for concerts in the summer. The books are then brought to the main library via a miniature railway.

"Some people have referred to it as a train, some people have referred to it as a rollercoaster, we just call it a conveyor," says Gerry Oliva, the library's Director of Facilities Management.

Gerry explains that the books were all measured, and placed into one of nine categories. They were then shelved based on that category.

You might think that arranging books that way would have Melvil Dewey spinning in his grave. But, of course, when he came up with his decimal system, nobody had heard of barcodes.

And even though the book storage system ends up putting Religion and Innovation: Antagonists or Partners? next to Oyster: A Gastronomic History, it saves the library 40 per cent in space.

So how do librarians find them?

When someone requests a specific book, they look up its barcode, which tells them the exact coordinates of the book's location in the stacks.

Then a robotic cart is dispatched along the railway to retrieve the book, and it is delivered to the scholar's hand -- fast.

"From the underground storage area to the main reading room, which is the furthest point, it's a little bit less than five minutes," Gerry says.



