What's most heartbreaking are the collections (public and private) known to have been destroyed, not by war, ignorance, revenge, or accident, but deliberately by the owners who lovingly assembled them ... just so that nobody else could ever enjoy them (usually via instructions in a will, but occasionally by the booklover's own hands) ... or by those who had good intentions and little more (most of the books collected during the French Revolution to be sorted and redistributed to form libraries for the people ended up ruined by crappy storage and lack of planning).
Polatron's research into this subject was triggered by the destruction of Sarajevo's National Library in 1992 (while many promises of aid to rebuild the collection were made by various countries, not one had been kept at the time of publication), and he used his time well ... this book is a wealth of information about the obscure as well as the familiar. Plus he's written chapters about modern-day library collection management practices, how we know what books have been lost, and about fiction about lost libraries (e.g. Eco's "The name of the rose"). All topped off by a quick reference chronology of significant library destructions through history and a marvelous bibliography. The only negative things I can think of about it are occasional awkwardness in the translation (the book was originally published in French in 2004) and the odd page where the proofreader seems to have nodded off ... happily both these things are infrequent and easy to forgive.
Defintely a must-read for anybody who loves books, reading, and/or libraries.