 The Meuse forts were armed with a total of 171 gun turrets, whose manufacture, transportation, and installation costed ₣24,210,775 in total.They were made of steel and placed in a concrete well in the massif or main redoubt.A turret itself sat on top a set of rollers, allowing it to turn 360°, and moved up and down its well with tracks running the length of the well.