Amsterdam, former emergency drinking water complex of the Defence Line of Amsterdam. The complex was built between 1901 and 1908 to provide drinking water for about 1 million people in times of war. After the Defence Line of Amsterdam was disbanded, the complex was put into use by, among others, KLM and Air Traffic Control the Netherlands, the location ensured interference-free radio communication with air traffic, the two transmission masts were later added for this purpose © 13 juni 2020 Aerophoto-Schiphol