At the confluence of the Meuse and Sambre, the citadel of Namur dominates the city of the same name. The site, which was used already as fortified town at the time of Aduatiques, acquired topography that we know to him today following the siege of Namur by the troops of King Louis XIV in 1692. It then was entirely rebuilt and strengthened by the Marshal of France Sebastien Le Prestre de VAUBAN.

The citadel of Namur, seen vrom the Meuse. This photograph is to be compared with the drawing from Robert Louis Marie de la Barque.

    Many curiosities characterize the citadel: its castle, the fortified place known as "Terra Nova", its moving plain and its theatre of "Greenery". However, the particular element which encouraged us to concentrate our effort was that the citadel hides in its entrails a gigantic network of undergrounds which one does not know at the present time all the extent. As many undergrounds which could without doubts lead towards another world.