Info here -
https://en.wikipedia.org/wiki/Cointe_Observatory

Update ( translation from news article ! )
"Good news for the people of Liège and for heritage lovers. The former ULiège Astronomical Institute, commonly known as the Cointe Observatory, will soon be classified. The Walloon Minister of Heritage, René Collin, has indeed decided to open the investigation with a view to the possible classification of this unique property in Wallonia and Belgium"