Heidelberg-Königstuhl State Observatory (German: Landessternwarte Heidelberg-Königstuhl) is a historic astronomical observatory located near the summit of the Königstuhl hill in the city of Heidelberg in Germany. The predecessor of the current observatory was originally opened in 1774 in the nearby city of Mannheim but degradation of observational conditions there resulted in a relocation to the Königstuhl in 1898.
The observatory forms part of the Center of Astronomy of the University of Heidelberg. The Max Planck Institute for Astronomy opened on an adjacent site in 1967. Andreas Quirrenbach is the observatory's director since 2005.
The instrumentation of the observatory originated from the Mannheim Observatory, founded in 1774. In 1880 the observatory was provisionally moved to Karlsruhe because the astronomical/atmospherical seeing conditions worsened. In subsequent years, three other locations were considered, with Heidelberg-Königstuhl finally being chosen.
On 20 June 1898 the "Großherzogliche Bergsternwarte" was ceremonially inaugurated by Frederick I, Grand Duke of Baden. The astronomical institute comprised two complementary departments, the astrophysical, led by Max Wolf, and the astrometrical led by Karl Wilhelm Valentiner. Valentiner was director of the Mannheim observatory and initiated the move to Karlsruhe. After Valentiner's retirement in 1909, both departments were placed under the administration of Max Wolf.