Schloss Klessheim is a Baroque palace located in Wals-Siezenheim, 4 km (2.5 mi) west of Salzburg, Austria. The palace was designed and constructed by Austrian architect Johann Bernhard Fischer von Erlach for Prince-Archbishop Johann Ernst von Thun in 1700. It became the summer residence of the Archbishops of Salzburg. Since 1993, the palace has been used by Salzburg Casino.

Wals-Siezenheim is a municipality in the district of Salzburg-Umgebung (Flachgau) in the Austrian state of Salzburg.