Fort de Chillon The Fort de Chillon is a twentieth - century fortification directly adjacent to the medieval Château de Chillon on the edge of Lac Léman in Switzerland . The fort secures the road and rail lines that pass along the lakeshore running east from Lausanne to the mountainous interior of Switzerland . The position is an advanced work protecting the approaches to Fortress Saint - Maurice , part of the Swiss National Redoubt . Deactivated as a military post in 1995 , it is privately owned and is being converted to a wine cellar . Description . The Fort de Chillon lies directly adjacent to the Château de Chillon , a major tourist attraction . The site has been fortified since at least the 12th century . The Fort de Chillon is a mixed infantry - artillery fort , located almost entirely underground in the steep slope rising to Veytaux above the rail line . The location is spanned by the Viaduc de Chillon . Built at the opening of the Second World War ( 1941 ) , it was armed with a mixture of 75mm guns and 90mm anti - tank guns . Initial work was completed in 1942 . The fort was designated A390 in the Swiss fortification nomenclature . The ensemble included permanent and rapidly deployable anti - tank obstacles , designed to stall or trap an enemy while the fort ' s weapons fired on them . The fort was initially armed with two 75mm anti - tank guns for direct fire , replaced with 90mm guns in 1962 . Two other 75mm guns were retained until 1978 . Two additional 90mm guns and five machine guns completed the offensive armament . Defensive arms included two machine guns each at the Rocher de Veytaux and Montagnette , with three at Champ - Babaud , along with two 81mm mortars . Infantry bunkers command the road and rail lines adjacent to the castle , linked to the main fort by underground galleries . The Fort de Chillon was manned by units of Mountain Brigade 10 . The garrison comprised 131 men . Nine detached bunkers were provided for infantry forces defending the surface of the installation . This position was covered from the direction of Saint - Maurice by the Fort de Champillon , an artillery fort . The Chablais plain to the south was covered by additional fortifications . The Chablais and Chillon ensembles were not considered part of Fortress Saint - Maurice proper , but were important advance works to delay and weaken an attacker before they reached the Saint - Maurice stopping line , or " fort d ' arrêt " . The entire region is fortified with anti - tank barriers , permanent minefields and other barriers , while tunnels , bridges and retaining walls are mined or prepared for demolition . Present status . As a result of the reorganization of Swiss fortifications under the Army 95 program , the fort was deactivated and declared surplus . Chillon was considered for purchase by the Canton of Vaud in 1998 and was briefly opened for public tours , with the intention of making it into a museum . However , the transaction fell through . The town of Chillon waived its rights in 2004 , followed by the neighboring town of Veytaux . In 2010 the property was purchased by investors who plan to make the site a wine storage facility and tasting facility . Tours may be instituted in the future .