The whole building is decorated by a light bossage, a simple string course, a weathering and a cornice.

The masonry is made up of local quarrystones with skilful working of the natural bossage.

Figure 4.4 shows a simplified flow diagram for the manufacture of batches of caustic soda, NaOH, from sodium carbonate by the bossage process.

The bossage entrance porch and the façades, as well as the roof of the keep, were defined as monuments historiques by the French Ministry of Culture on 25 July 1973.

The different features on the bases is noteworthy, especially at the downstream side and partially at the upstream side of the bases on the east section of the bridge where the bossage wall technique was used, there are flood splitters and bars designed as stairs.