Defence Line of Amsterdam

The Stelling van Amsterdam ( pronounced [ˈstɛlɪŋ vɑn ˌɑmstərˈdɑm]; "Defence Line of Amsterdam") is a 135-kilometre (84 mi) fortification line around Amsterdam, which would function as a national redoubt. It comprises 45 forts, as well as dams, dikes, locks, pumping stations, batteries and casemates. The forts are 10–15 kilometres (6.2–9.3 mi) from the centre and lowlands, which can easily be inundated in time of war. The inundation was designed to give a depth of about 30 centimetres (12 in), too little for boats to cross. Any buildings within 1 kilometre (0.62 mi) of the line had to be made of wood so that they could be burnt and the obstruction removed.

The Stelling van Amsterdam was constructed between 1880 and 1920. The Stelling was mobilised and partially inundated during the First World War, but the Netherlands remained neutral and was not invaded. In 1922, the Stelling became part of the Fortress Holland [nl]. The north side of the Stelling was inundated when Germany invaded in 1940 at the start of the Second World War, but the Netherlands capitulated before the Germans reached the Stelling.