The Mannheim Observatory was a tower observatory built between 1772 and 1774 in Mannheim, Germany, which remained in operation until 1880. The observatory was transferred to Karlsruhe and finally in 1898, was established on the Königstuhl near Heidelberg where today's successor institution the State Observatory Heidelberg-Königstuhl is located.
The observatory tower is now owned by the city and was restored in 1905–1906, and after the Second World War. Since 1958, the tower houses studio flats.
Wikipedia https://en.wikipedia.org/wiki/Mannheim_Observatory
Coordinates 49°29'11.404" N 8°27'34.921" E