Hegra Fortress Hegra Fortress ( ) is a small mountain fortress in the village of Hegra in the municipality of Stjørdal in Nord - Trøndelag county , Norway . Originally known as " Ingstadkleiven Fort " ( also " Ingstadkleiva Fort " ) , it was built between 1908 – 1910 as a border fort as a defence against the perceived threat of a Swedish invasion . Background . The intent behind Ingstadkleiva Fort was to block Swedish advances into Central Norway , as had happened repeatedly during the Swedish - Norwegian conflicts in the preceding centuries ( see : Hannibal War , Northern Wars , and Great Northern War ) . After the 1905 dissolution of the union between Norway and Sweden , the Norwegian military harboured continued fears of a Swedish invasion to retake Norway . As a successful attack into the centre of the country could split it in half , the Norwegian general staff in February 1906 suggested the construction of a blocking fort in the Stjørdalen valley . Ingstadkleiva was early on pointed out as a good location to block an advance from the east . Already in March that year the Minister of Defence , commanding general , and chief of the Fortress Artillery surveyed the site and agreed to the plan . In a closed meeting on 26 April 1906 , the Norwegian Parliament authorized the construction of Ingstadkleiva Fort , but no funds were allocated until 12 July 1907 . In May 1908 , the work began on the road up to the construction site and by January 1910 the fort was ready for use . Geography . The fort was built on , and named after , Ingstadkleiva — a high forested hill south of the Stjørdalselva river , about from the village of Hegra . To the east , north , and north - west the terrain slopes down towards the Stjørdalen valley and is dominated by the fort , while the south front is hilly and at a higher altitude than the Ingstadskleiva . Ingstadkleiva Fort has an excellent command of the Stjørdalen valley to the north and east , but to the west the view is blocked by the Grøthammeren and Hammeren hills , both about high . Ingstadkleiva Fort . The fort ' s guns came from the dismantled Ørje Fortress in Marker . The artillery was made up of flat angle guns with a range of . The fortifications themselves consisted of of halls and tunnels dynamited into the mountain at Ingstadkleiva , as well as trench systems and gun positions excavated from the rock with explosives . There are two main underground parallel tunnels of around length , with a tunnel connecting them at a straight angle . One of the main tunnels served as crew quarters while the other was in direct connection with the above ground artillery pits . The fortress ' artillery consisted of two and four positional artillery pieces in half - turrets placed in pits dynamited from the rock and lined with concrete , as well as four Krupp M / 1887 field gun s . The pieces , designed before the advent of recoil systems , were described by the Germans after the 1940 surrender as " Napoleonic " . The positional artillery is placed in an almost straight line facing east , with a distance between each gun and between each piece . To enable the fortress to withstand attack without support from outside a wide barbed wire obstacle was constructed encircling the entire fortress . Early period . During the period 1910 to 1926 the fort was used as a major military base for the Trøndelag border areas with Sweden . In 1926 , Ingstadkleiva Fort was put in reserve as part of the post - World War I defence budget cuts . Deactivated period . From 1934 – 1939 , the deactivated fort was used by the Norwegian Red Cross ' s youth branch as a summer holiday camp for children . In late 1939 , Finnish soldiers of the independent Lapland Group who had crossed the Norwegian border into Finnmark escaping the fighting in the Petsamo district in northern Finland were interned at Ingstadkleiva Fort . All the Finns were repatriated during the early days of 1940 . During the Finnish internees ' stay a sauna was constructed at the fort ' s camp . Norwegian Campaign . In 1940 , from 15 April to 5 May , Hegra was attacked by the German invaders . During the first week the attacks consisted of two infantry assaults ; however in the last two weeks attacks mostly featured heavy artillery fire and Luftwaffe bombing , as well as aggressive patrolling . During the siege large portions of the fort were covered in snow , and as all plans of the fort were stored in German - occupied Trondheim several sections of the fortifications were not discovered by the defenders before the 5 May surrender . Present - day fortress . After the end of the Second World War , Hegra Fortress was returned to Norwegian control and is today used as a museum with exhibitions detailing the fort ' s history with an emphasis on the 1940 siege . There is also a café and a souvenir shop . The museum is often used for conferences and for seminars on issues of war and peace . Hegra Fortress is still owned by the Norwegian Defence Force and financed through the Norwegian Ministry of Defence . Hegra Rifle Association has since 13 May 1962 held an annual shooting competition at the fortress . Organized in commemoration of the 1940 battle and of the Second World War in general , the competition is held on the Sunday closest to 8 May ( VE Day ) . The casing of a shell fired at the fortress in 1940 is awarded to the competition winner each year as a travelling trophy .