Schloss Niederfladnitz is a 16th-century castle in the Waldviertel region of Lower Austria, now part of Hardegg within Thayatal National Park. Originally a farmstead for the Eyczing family's estate administration, it was expanded into a castle featuring a distinctive Late Renaissance gate and an octagonal central tower in its courtyard. The simple single-story structure is characterized by two round corner towers topped with tall cupolas, reflecting its origins as an administrative center rather than purely representational architecture. The castle passed to the Trautson family in 1615 and later to the Auersperg family in 1775, with portions now owned by the municipality.
