Very steep stairs, so when arriving at the top you’ll be out of breath (don’t forget to take a bottle of water with you). But really worth doing so when visiting Liège. It is really a must see. The view is beautiful and you’ll be proud of your own accomplishment!
Montagne de Bueren
Visited July 2017. You can find my review about Montagne de Bueren also on TripAdvisor.