To be privately owned
Palais Schwarzenberg

The Palais Schwarzenberg in Vienna-Landstraße is one of the Baroque garden palaces in the Austrian capital. Originally started as Palais Mansfeld-Fondi, it was designed by architects such as Johann Lukas von Hildebrandt, Johann Bernhard Fischer von Erlach, and Joseph Emanuel Fischer von Erlach.
History+
The origins of the palace date back to 1697, when Grand Marshal Heinrich Franz Graf von Mansfeld and Prince of Fondi commissioned Johann Lukas von Hildebrandt to build it. The shell construction was completed in 1704. After the death of Count Mansfeld, Adam Franz Karl Prince of Schwarzenberg acquired the unfinished estate in 1716.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://en.wikipedia.org/wiki/File:Palais_Schwarzenberg.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: 48.1969, 16.3770