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—a two-winged structure reaching beyond the Ringstraße, with the twin museums (Kunsthistorisches Museum and Naturhistorisches Museum as flanks and terminating at the old Imperial Stables of Fischer von Erlach. The museums were completed in 1891, but construction of the rest of the forum dragged on slowly and conflicted since, besides ostentation, no real function could be found for the enormous construction project. In 1913, the south-west wing, the Neue Burg ("New Castle") was completed. However, the Imperial Forum was never finished. The Neue Burg today houses a number of Collections, that belong to the Kunsthistorisches Museum Vienna: the Ephesus Museum, the Collection of Arms and Armor and the Collection of Ancient Musical Instruments. The Collection of Arms and Armour numbers among the best of its kind in the world. Furthermore, it is the best-documented collection of court arms and armour in the western world, since the exhibits were generally created or acquired in connection with important political occasions: on the occasion of military campaigns, Imperial Diets, ceremonies of homage, coronations, engagements, marriages and baptisms. No family of rulers was connected by marriage with so many European countries as were the Habsburgs. For this reason, nearly all western European princes from the 15th to the early 20th centuries are represented with armour and ornamental weapons. The suits of armour are custom creations made by the most famous armourers: the Armour for a Horseman by Tommaso Missaglia, the Cuirassier Armour by Lorenz Helmschmid for Emperor Maximilian I, the Boy's Folded Skirt Armour by Konrad Seusenhofer for the future Emperor Charles V, as well as the Half-Armour alla Romana by Filippo Negroli and many others. The often magnificent etchings were quite frequently based on designs by such famous artists as Dürer and Holbein.