Short answers, pulled from the story.
The main Nazi book burnings took place on the 10th of May 1933, in thirty-four university towns across Germany. Some events were postponed due to rain, and others took place on the 21st of June 1933, the summer solstice. The campaign had been announced on the 8th of April 1933 by the German Student Union.
Over 25,000 volumes were burned in Berlin alone at the Bebelplatz square on the 10th of May 1933. The campaign targeted around 4,000 titles, aiming to destroy every copy available. In occupied Poland, the destruction was far larger, eliminating an estimated 80% of all school libraries and three-quarters of all scientific libraries in the country.
The Nazi book burnings were organized by the German Student Union, known as the Deutsche Studentenschaft. Its Main Office for Press and Propaganda announced the nationwide campaign on the 8th of April 1933. Propaganda Minister Josef Goebbels spoke to some 40,000 people at the Berlin burning and his speech was broadcast on the radio.
Books burned included works by Albert Einstein, Sigmund Freud, Bertolt Brecht, Karl Marx, Erich Maria Remarque, Thomas Mann, Heinrich Mann, Helen Keller, Ernest Hemingway, and Magnus Hirschfeld, among dozens of others. The lists covered Jewish authors, communists, pacifists, liberals, and anyone whose work the Nazis deemed incompatible with their ideology.
The Library of the Burned Books was founded by Alfred Kantorowicz and opened in France on the 10th of May 1934, exactly one year after the Berlin burnings. It collected banned and burned titles and served as a center for anti-Nazi intellectual activity. After the fall of France, the Nazis seized and destroyed it.
The Empty Library, created by Israeli artist Micha Ullman in 1995, stands at Bebelplatz in Berlin where the original burning took place. It is an underground room of empty bookshelves visible through a glass pane in the square. Bronze plaques nearby bear Heinrich Heine's 1820 warning: "Where they burn books, in the end they will also burn people."