Uninhabited
Baumgarten Castle

In Vienna's 14th district of Penzing stands Baumgarten Palace. Originally designed as a residence, it was later transformed into an event venue and now houses a recording studio.
History+
Baumgarten Palace dates back to 1779, when it was built by General Andreas Hadik von Futak. The property changed hands several times and was at one point owned by the Princes of Esterházy. In the 19th century, the palace underwent a transformation into a casino and was extended in 1891/92 with a large ballroom in the Historicism style. Later, Baumgarten Casino came into the possession of the SPÖ through a donation, which transferred it to the Association of Viennese Workers' Homes.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Casino-baumgarten-1.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 48.1968, 16.2768