Westwall (Siegfried Line) was a series of fortifications in the western border of Germany.

Westwall was, at least in part, built by slave labour, see Hinzert-Bad Nauheim).

More research is needed on which bunkers were built by slave labour and where the enslaved people were stationed (Concentration camps, Westlager, etc)

• https://www.festungen.info/content/bunker/westwall/