This is the most popular area in Belgium.
It includes some of the highest walls (300 ft) for several hundred miles around.
But more importantly it is large, has a long history and has a wide varietity of excellent routes.
The rock is hard limestone which has become rather polished in the easier classics from the first half of the previous century.
There is a cheap campsite right on top of the crag.
There are easy routes (4a) although these can be slippery and tend to be rather run out. The area also has many medium and hard routes, right into the 8th grade.