Hitler's strategy was straightforward in its ambition. By placing massive coastal batteries on both sides of the Skagerrak, Germany could deny Allied naval forces access to Eastern Norway, the Kattegat, and the entire Baltic Sea. The decision about the Danish side came first, in May 1940, when the fortress at Hanstholm was authorized. By May 1941, two guns were operational there, and preparatory work began on the Norwegian side at Movik. Between 1941 and 1944, the German navy built what they called Batterie Vara, naming it after Major General Felix Vara, killed off Alderney in the English Channel on 3 November 1941. Together with four other coastal batteries, it formed the Kristiansand Artillery Group. The twin fortresses left only a ten-nautical-mile gap in the Skagerrak uncovered by their guns. That gap was filled with mines.

The four 38 cm guns installed at Movik were not originally meant for a hilltop in southern Norway. They were naval guns, the same type fitted to Germany's Bismarck-class battleships, and had been intended for the battleship Gneisenau. When Gneisenau was damaged in a bomb raid, the decision was made to mount the guns in concrete fortifications instead. Each gun position weighed 650 tonnes in total, and the weapons were shielded behind 3.5 meters of reinforced concrete, bristling with anti-aircraft defenses. They could fire a 495 kg projectile 55 kilometers, or send an 800 kg shell 42 kilometers. The rate of fire was one round every ninety seconds. The largest cannon of all never arrived at Movik; the cargo ship carrying it was sunk in the Kattegat in February 1945, just months before the war ended.

After liberation, the Norwegian Armed Forces renamed the installation Movik Fort and kept it operational for several years. In 1953 it became part of the larger Kristiansand fortress complex. But the age of massive coastal artillery was passing. On 20 April 1959 the fort was officially closed, and two of the four guns were scrapped along with the foundations of the fourth. One gun survived, standing as a monument to an era of warfare defined by industrial scale and brute force. For decades, it simply sat there on the headland, a relic that passing ships could see but few visitors understood.

Plans for a museum took shape in 1984, driven by those who recognized the fortress as more than scrap metal. Through the late 1980s and early 1990s, local armed forces and the Foundation Kristiansand Cannon Museum Movik carried out extensive renovation work. The foundation was formally established in 1991, and today the museum is administered by the Nasjonale Festningsverk, Norway's national fortifications authority. Visitors walk the Fortress Trail, a path through gun emplacements, empty casemates, and the buildings where German soldiers lived their daily lives under the constant awareness that they were manning one of the most powerful coastal batteries in occupied Europe. The surviving gun stands at the trail's center, its barrel angled toward the sea as it has been for over eighty years.