Fort Island Pampus was built between 1887 and 1897. To defend Amsterdam a military master plan was conceived, the Defense Line of Amsterdam. Against an attack from the River IJ it was decided to build a fortress in the Lake IJmeer. This was to be located on the sandbank “Pampus”. The first stage of the building was to lay down a work platform where the centre of the fort would stand. The vast quantities of material were delivered by ship out of Amsterdam. A German Company built the steel gun turrets.