The Telegrafenberg is a forested hill south of Potsdam city centre, home to a campus of scientific institutes that has been a centre of geophysical and meteorological research since the 1870s. The hill takes its name from an optical telegraph station that once relayed signals from Berlin westward. Today the campus includes several 19th-century observatory buildings, a meteorological station, and most famously the Einsteinturm — the expressionist solar observatory designed by Erich Mendelsohn in 1920.
The walk up to the summit takes about twenty minutes from Potsdam Hauptbahnhof, through a nature reserve of mixed forest with good views back towards the city. Guided tours of the campus and the Einsteinturm run on Saturdays in season and must be booked in advance. The hill itself is open at all times, and the views from the summit across the Brandenburg landscape and towards the Potsdam palace towers are worth the walk even without a tour.