Observatories with public access in Europe This is a follow-up to Observatories that allow public access with a smaller (geographical) scope.
I am interested in getting to know observatories in central Europe (e.g. France, Germany, Poland, Switzerland, Austria) where you could could go with a class of school children or university students.
Maybe you could add more entries to my list, please?

The Effelsberg radio telescope has a visitor programme.
The Heidelberg observatory has some outreach programme, but is close to a city with its lights.
Similar problems with light pollution has the Paris Observatory.

I tried to find some European website with such a list, but I was not successful yet.
There are plenty of possibilities - and often, even when not publicly advertized, many observatories will be very open to find an arrangement when approached, especially by a group of interested audience. So this list IMHO would be the complete list of possible observatories found in central Europe.
The wiki page on astronomical outreach resources in Europe has such list of observatories (well, for the whole world, but filter it) - mostly the professional ones; of course it's not complete, e.g. the Thuringian observatory at Tautenburg is missing (who also offer regularily public tours) as does the GEO600, the gravitational wave observatory near Hannover.
There are various lists for amateur associations, many have their own observatory, e.g. this one lists many in the DACH countries sorted by post code.