Barbed wire protects a bunker at former Swiss artillery fortress Reuenthal near the village of Reuenthal, Switzerland July 18, 2015. Reuenthal fortress, located on the Swiss-German border near the rivers Rhine and Aare was built from 1937 to 1939 and remained in military use until 1988. Since 1989 it has been open to the public as Fortress Museum Reuenthal. With the threat of foreign invasion a thing of the past, thousands of military bunkers and fortresses in Switzerland have been put to commercial use, from hotels to data centres, museums to cheese factories. The Swiss army has sold most of these decommissioned strongholds, but about a thousand unused bunkers remain, many still disguised as houses and barns. REUTERS/Arnd Wiegmann PICTURE 21 OF 27 - SEARCH "SWISS BUNKER" FOR ALL IMAGES