Yes, before you start wondering, there is yet another castle or palace with the name Liechtenstein. Schloss Liechtenstein is located directly behind Burg Liechtenstein - well, depending on which side you are standing, really - and is one of the gazillion castles and palaces once owned by the Princely Family in the Austro-Hungarian Empire. Fun fact: Approximately about 15 or 20 are still owned by the family or one of their foundations. Schloss Liechtenstein though is not one of them.
In 1596, Georg Wiesing, who you probably don't recall as the administrator of Count Hans of Khevenhüller-Frankenstein from the post about Burg Liechtenstein, had a Meierhof, a farm or building occupied by the administrator (the Meier) of a noble or ecclesiastical estate, built in place of today's Schloss. At that time, the ancestral home of the Liechtenstein family in Maria Enzersdorf wasn't owned by them. Instead the owner was Hans of Khevenhüller-Frankenstein, who had been given the area as a fiefdom by Emperor Rudolph in 1592.
In 1820, Prince Johann commissioned architect Josef Engel, a student of Joseph Kornhäusel, to build a Biedermeier-style summer residence for the Princely Family just opposite of their ancestral home. Previously, a Baroque castle with a small tower had stood in its place, at least according to a 1795 painting by Johann Christian Brand. Inspiration for the summer residence was taken from Schloss Weilburg in Baden near Vienna, which Archduke Karl of Austria had gifted his wife, née Princess Henriette of Nassau-Weilburg. (Yes, the royal world is small
Today's Schloss is a rather simple, three-storey building. The side facing the Burg features a nine-axis classicist central section and high round-arched windows and doors on the main floor. The gable of the central pillared loggia is adorned by the coat of arms of the Princely Family, who regularly spent time at Schloss Liechtenstein prior to the Second World War, who sadly brought about its demise.
In 1945, the Schloss suffered heavy war damage and was later used by the Red Army before it became a reception centre for Hungarian refugees in 1956. By the 1960's, it was in such a desolate condition and uninhabitable that a total demolition was considered in 1964, despite it being under monumental protection since 1939. The largely-ruined Schloss Liechtenstein, parts of which had actually been demolished, was later sold by the Princely Family and turned into a retirement home. After long restoration and some more demolition works, only the central part of the original 19th century summer residence still remains.