For a depressing read, Wikipedia has an article on the great destroyed libraries of the world, from 206 BCE to 2015 CE. There seems to be no indication that libraries are any more immune to destruction in modern times, and it isn’t just Nazis or religious fanatics doing the burning. The British burned down the Library of Congress in 1812 and towards the end of the 19th century burned down the royal library in Burma. Leftists and anarchists burned many libraries in Spain in 1931. In Canada, in 2013 "scientific records and research created at a taxpayer cost of tens of millions of dollars was dumped, burned, and given away," under the government of Stephen Harper.