Fort aan den Ham is a fort of the Defence Line of Amsterdam. It is located on the railway line from Uitgeest to Krommenie. The earthen ramparts, the first part of this defence work, date from 1896, the fort itself was completed in 1903. Originally, this fort was not included in the plans of 1880, but this became necessary due to the newly formed access that arose after the construction of the Amsterdam – Alkmaar railway line. Because this railway line between Uitgeest and Krommenie was on a slope, exactly between the larger forts Veldhuis and Krommeniedijk, a fort was built next to this railway line to control this railway embankment. The fort closed off these entrances in wartime.
In 1896, earthen ramparts were constructed on the fort site and in 1902-1903 the bomb-proof buildings followed.[1] In 1908, a concrete secondary battery was built south of the fort.[1] Heavy guns were placed here to fire at the approaching enemy from a greater distance. The adjacent Rijksweg, the current N203, was completed in 1934 and runs parallel to the railway line.