Workers build fortifications of Siegfried Line on western border of Germany

High angle pan men pulling machine with ropes / men standing on machine / men carrying bags of concrete mix / men walking along foundation trench / VS machinery in operation / metal molds for concrete foundation / man using acetylene torch / man using large wrench to tighten nut / line of men passing metal bar from one to another / fortification under construction / MPOV of underground tunnels / men in tunnel / Note: exact day not known