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When the New York Public Library opened on Fifth Avenue in 1911, thousands of people lined up outside the palatial Beaux-Arts building to get their hands on books they could find nowhere else.

There were rare first editions of classics like “The Scarlet Letter,” political treatises and hand-scribbled family histories, all stored within easy reach in seven football-field-size floors of stacks just below the main reading room.

But over the next century, the stacks became outdated and could not adequately protect irreplaceable books from sunlight, heat and humidity, library officials said.

The books were taken away in 2013 as part of the library’s plan to replace the stacks with a new lending library, which drew howls from prominent authors, scholars and many patrons.