The Berlin Observatory
The original location of the Berlin Observatory, shown on this map as Markthalle II:
The Berlin Observatory first opened in 1835 and was eventually moved and split into several locations across Berlin and even other parts of Germany, like the Babelsberg Observatory in Potsdam. On September 4th, 1846, it was the site of the planet Neptune's discovery by Johann Gottfried Galle and his student, Louis d'Arrest.
Sources:
https://www.rmg.co.uk/stories/topics/astronomy-19th-century
Parent Map
Coordinates
Latitude: 52.503837810968
Longitude: 13.391819000244
Longitude: 13.391819000244