I just stumbled on this:
panoramio.com/photo/61678611
panoramio.com/photo/36243631
It seems that it is the castle of Lucien's Folly today 
Of ArM4 fame. It is in the correct location, at least.
Cheers,
Xavi
Very cool! Looks like they repaired that top floor... 
it does indeed
Strictly Triamore is on the other side of the river from Spontin - I reckon it is closest to Givet, though the topography is a little out.