Hofburg
Following the enlargement of Vienna after the demolition of the city walls in the 1860s, the Hofburg had its last great expansion. An Imperial Forum (Kaiserforum) was planned, in which a two-winged structure reaching beyond the Ring Road, with the twin museums (Kunsthistorisches Museum and Naturhistorisches Museum) as flanks and terminating at the old Imperial Mews (the Hofstallungen, not to be confused with the much older Stallburg) of Fischer von Erlach. In 1913, the south-west wing, the New Castle (Neue Burg), was completed. However, the Imperial Forum was never completed and remains a torso. The New Castle wing today houses a number of museums (the Ephesos Museum, the Collection of Arms and Armour, the Collection of Ancient Musical Instruments, and the Museum of Ethnology) as well as some reading rooms of the national library. The Hofburg Congress Centre is also located here.