The Castle can be visited
Museum
Eckartsau Castle

The historic hunting lodge Eckartsau Castle is situated in Eckartsau, in the Danube wetlands of the Lower Austrian Marchfeld region. Its history is closely linked to the final days of the Austro-Hungarian monarchy, as it served as the last residence of Emperor Karl I before his exile.
History+
The origins of Eckartsau Castle trace back to a four-sided moated castle owned by the noble family of Eckartsau. Heinrich des Ekkarisowe is first mentioned as a witness in a deed of gift. The Eckartsau family, who were feudal subjects of the Prince-Bishopric of Regensburg, expanded their possessions to include market rights and other castles. Konrad von Eckartsau received support under Duke Albrecht V. Despite plunderings under Emperor Friedrich III, Georg von Eckartsau himself was known as a robber knight. After the death of the last male Eckartsau, Wilhelm, the heirs sold the estate in 1571 to Georg Freiherr von Teuffel. After changes of ownership, Franz Ferdinand Graf Kinsky acquired the castle in 1720 and had it converted into a hunting lodge according to plans by Joseph Emanuel Fischer von Erlach.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Eckartsau_Schloss.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: 48.1404, 16.7940