Schloss Welsbach, Cultural heritage castle in Mölbling, Austria.

Schloss Welsbach is a two-storey late historicist building in Rastenfeld, Mölbling, modelled on French Renaissance town palaces. It has a six-axis central section and four-axis wings with tower-like corner risalits. The elongated facade is strongly articulated, with rusticated projecting corners, a strong cornice between floors and stone-framed windows. A large park with a greenhouse and an orangery surrounds it.

Industrial magnate Carl Auer von Welsbach commissioned architects Anton and Josef Bierbaum to build the castle between 1898 and 1900 on the grounds of the former Villa Marienhof. This construction followed the success of his industrial ventures.

The interior retains its original representative furnishings almost unchanged: the staircase, tiled stoves, floors and doors from around 1900. Carl Auer von Welsbach lived in the house until his death in 1929, and it is still owned by his descendants, so the rooms are not open to visitors.

The castle remains privately owned by descendants of Carl Auer von Welsbach and is not open to the public. Visitors can view the exterior facade and surrounding gardens from outside.

The site was previously Villa Marienhof, the summer retreat of Viennese operetta singer Marie Geistinger, who sold it to Carl Auer von Welsbach in 1893. Auer lived in the castle until his death in 1929, and it remains in the hands of his descendants. The park retains outbuildings such as a greenhouse and an orangery.