|Bundesland: Niederösterreich||Lower Austria|
Rosenau is situated at an elevation of 628 m in the district of Zwettl in the western Waldviertel region of Lower Austria. A castle at Rosenau was already mentioned in 1194. Rosenau Schloss and Rosenau Dorf are cadastral districts of the municipality Zwettl.
The present castle Rosenau [left] was built 1593 in Renaissance style. Count Leopold von Schallenberg had the castle remodelled in Baroque style in 1736–1747. Since 1975 the castle houses the Austrian Freemasonry Museum in the original rooms of a Masonic lodge of the 18th century. The chapel of the castle also serves as parish church (Heilige Dreifaltigkeit, Trinity church). The ceiling fresco showing the Adoration of the Trinity is attributed to the famous Austrian painter Paul Troger (1698–1762).