There is a tiny climbing area in an abandoned stone pit near Kelmis. It’s right around the corner from Aachen, where yours truly lives, so me and my fellow citizens can be found there sometimes. Unfortunately information regarding the climbs is rare. I managed to unearth a bare bones topo from the Internet Archive, which I’m publishing here for download. Judging from my own experience, the grading is sort of accurate, but the climbs at the outer left part of the main wall are missing. I’ve however heard that a guy from Belgium is working on documenting them as well.
Disclaimer: If have no idea where the topo originally came from and I take no responsibility for its correctness.
If you are the creator of the topo and want attribution of some sort (or if you want me to take down the link), please get in touch.