The Nevenbatterij van het Fort bij Hoofddorp is a part of the Defence Line of Amsterdam. Work began on the defence line in 1880, and the entire defence line project was completed by 1920. The defence line consisted of a network of forts, earthen batteries, pumps, and dykes, that could be used to defend key strategic points, and flood certain areas to hamper enemy troop movement. The defence line is now a Unesco protected monument.
