I found this library by chance in Gorlitz. It was about 2 doors down from our apartment in a small museum. I was wondering around the museum when a security guard called me, took me up a flight of stairs and through a few doors for me to see this beautiful room. I was surrounded by rows and rows of books going into the distance.
If you want to see the library you have to know to look for it; you can find it here: Barockhaus Neißstraße 30 Kulturhistorisches Museum Görlitz. In the museum you might need to ask somebody to take you to the library, its magnificent.