Overview of military defensive lines in the Netherlands in may 1940.
Disclaimer: The exact location of the forts and lines may differ from reality to a slight extent.
<a href="//commons.wikimedia.org/wiki/User:NielsB" title="User:NielsB">Niels Bosboom</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>