The building was, however, not very popular with the public. On the one hand, it did not seem as grand as the Heinrichshof, a private residence which was destroyed in World War II (and replaced in 1955 by the Opernringhof). Moreover, because the level of Ringstraße was raised by a metre in front of the opera house after its construction had begun, the latter was likened to "a sunken treasure chest" and, in analogy to the military disaster of 1866 (the Battle of Königgrätz), was deprecatingly referred to as "the 'Königgrätz' of architecture". Eduard van der Nüll committed suicide, and barely ten weeks later Sicardsburg died from tuberculosis so neither architect saw the completion of the building. The opening premiere was "Don Giovanni", by Mozart, on 25 May 1869. Emperor Franz Josef and Empress Elisabeth (Sissi) were present.