Camouflaged Military Bunkers of Switzerland (2015)
Fun Fact: The Swiss once lost tanks in their underground networks. Around 400.<p><a href="https://www.nzz.ch/maurers_schimmelnde_panzer-1.8120259" rel="nofollow">https://www.nzz.ch/maurers_schimmelnde_panzer-1.8120259</a>