Unfortunately we did not see the lifts in action and in such a case it is not a WHS with a big wow-factor.
However, it's a nice walk along the old canal du centre - walking from lift 1 to 3 is about 3 km - and every lift itself is an impressive piece of machinery.
There are three other WHS nearby (Mining sites of Wallonia - Bois du Luc, Neolithic flint mines at Spiennes and the Mons belfry) and all of them are free of charge every first Sunday of the month. Taking this into account, the La Louvière/Mons region is worth a visit.