Schloss Heiligenkreuz, Gutenbrunn, Protected heritage castle in Gutenbrunn, Austria.

Schloss Heiligenkreuz is a three-winged castle of two to four storeys in Gutenbrunn, with a 15-axis north wing flanked by two octagonal corner towers that rise one storey above the roofline. The east wing incorporates the Marienkapelle, a domed central space with a semi-circular apse, and the south wing is formed by the parish church of Mariä Himmelfahrt. The plain four-storey west wing was built as an alumnate.

Josef Johann von Tepsern had a Marian chapel built on the east front between 1733 and 1735; the north and east wings followed around 1740/1760. In 1754 auxiliary bishop Anton Marxer bought the estate and added the west wing as an alumnate, used until 1783. The Figdor family owned the castle until 1858; bomb damage occurred in 1945.

The south wing of the castle is the parish church of Gutenbrunn-Heiligenkreuz, dedicated to the Assumption of Mary, which also serves as a pilgrimage church. The former Marienkapelle, integrated into the east wing around 1740/1760 as the private chapel of auxiliary bishop Anton Marxer, preserves ceiling and wall paintings by Paul Troger from 1735, including a dome fresco of the Assumption with the Holy Trinity and pendentive figures of Judith, Esther, Jahel and Pharaoh's daughter.

The castle stands in the Schlossweiler Heiligenkreuz, part of Gutenbrunn in the municipality of Herzogenburg, Lower Austria. Its south wing is the parish church of Gutenbrunn-Heiligenkreuz, so the church can be visited independently of the former museum rooms. The Baroque museum in the north and east wings, opened in 1964, was closed in 2001.

The north and east wings held the Lower Austrian Baroque Museum from 1964 until its closure in 2001. The museum was set up by the Lower Austrian State Museum, and the castle had suffered bomb damage in 1945 before that.