La Coupole, originally codenamed Bauvorhaben 21 (Building Project 21) or Schotterwerk Nordwest (Northwest Gravel Works), is a Second World War bunker complex. It was built by the forces of Nazi Germany between 1943 and 1944 to serve as a launch base for V-2 rockets directed against London and southern England, and is the earliest known precursor to modern underground missile silos still in existence.
Constructed in the side of a disused chalk quarry, the most prominent feature of the complex is an immense concrete dome, to which its modern name refers. It was built above a network of tunnels housing storage areas, launch facilities and crew quarters. The facility was designed to store a large stockpile of V-2s, warheads and fuel and was intended to launch V-2s on an industrial scale. Dozens of missiles a day were to be fuelled, prepared and launched in rapid sequence against London and southern England.
Following repeated heavy bombing by Allied forces during Operation Crossbow, the Germans were unable to complete the construction works and the complex never entered service. It was captured by the Allies in September 1944, partially demolished on the orders of Winston Churchill to prevent its reuse as a military base, and then abandoned. It remained derelict until the mid-1990s. In 1997 it opened to the public for the first time, as a museum. Exhibits in the tunnels and under the dome tell the story of the German occupation of France during World War II, the V-weapons and the history of space exploration.References:
Kristiansten Fortress was built to protect the city against attack from the east. Construction was finished in 1685. General Johan Caspar von Cicignon, who was chief inspector of kuks fortifications, was responsible for the new town plan of Trondheim after the great fire of 18 April 1681. He also made the plans for the construction of Kristiansten Fortress.
The fortress was built during the period from 1682 to 1684 and strengthened to a complete defence fortification in 1691 by building an advanced post Kristiandsands bastion in the east and in 1695 with the now vanished Møllenberg skanse by the river Nidelven. These fortifications were encircled by a continuous palisade and thereby connected to the fortified city. In 1750 the fortress was modernized with new bastions and casemates to protect against mortar artillery.