A fine and distinctive building in the Old Town centre it has been gazing at the stars since 1907. Interestingly it was the first of the city’s building to be made entirely of concrete. Its 50 metre high observation tower has within it an impressive twelve ton Zeiss telescope that provides magnifications by a factor of around 600.

This is a real, fully-functional observatory built over 100 years ago, with a relatively large telescope and two smaller ones on either side. A presentation was given by an actual professor of astrophysics and we took it in turns to use the telescopes to observe distant objects. The professor rotated the dome as well as the viewing platform at times to adjust to the telescope's orientation - not something you see every day. It was impressive even considering that there was still daylight and it was a cloudy day. It must be fantastic in the wintertime on a dark, clear night. The tours are usually in German but once in a while they do one in English, so check before you go. Honestly I'd give this five stars if not for their ticketing partner, EventFrog, which is a nightmare. It's only in French/German, very confusing, and at times doesn't work at all (e.g. the link to the online ticket stopped working a while ago, and the PDF download link wasn't working a day before the event, so good thing I had downloaded it beforehand). There is also the Jules Verne panoramic bar but this was closed at the time of my visit. I suppose it would have been nice as well. You can still enjoy views of the city from the observatory itself.