Former fortifications at Mandling, a village at the border of federal states Salzburg (with city of Radstadt) and Styria (city of Schladming). The tunnel to Filzmoos runs parallel to the Mandlingbach. It was built by French POWs in 1941 (acc. to info plaque).
<a href="//commons.wikimedia.org/wiki/User:Herzi_Pinki" title="User:Herzi Pinki">Herzi Pinki</a>
CC BY-SA 3.0 at
<span class="int-own-work" lang="en">Own work</span>