A beguiling exploration of the last Habsburg monarchs' grip on Europe's historical and cultural imagination. In 1919 the last Habsburg rulers, Emperor Karl and Empress Zita, left Austria, going into exile. That same year, the fairy-tale opera Die Frau ohne Schatten (The Woman Without a Shadow), featuring a mythological emperor and empress, premiered at the Vienna Opera. Viennese poet Hugo von Hofmannsthal and German composer...