The Iron Man (Geodetic Point Kesterheide)

This is the highest point in the province of Flemish Brabant, 111.86 metres. This geodetic point, which has been here for a century and a half, is popularly known as 'the iron man'. The explanation for this is obvious, given the shape of the clock casing. However, the actual measuring point is inside that metal carcass. Originally, the 'iron man' stood on a brick pedestal, which was replaced by concrete a long time ago. The measuring point was already placed on the Kesterheuvel in 1863 (1867?) as a 'station géodésique', it served as an orientation reference for determining height and position for Belgian cartography.
The ball or 'bullet' was visible from far away in the 19th century. The view at the foot of the Iron Man was magnificent. Today, part of the view is hidden by the forest. At the beginning of the 20th century this was not the case, almost the entire Kesterheuvel had been cleared.
(Trekkings.be)

The Iron Man on the Kesterheide is the name given to a triangulation point that was used for the creation of staff maps by the Dépôt de la Guerre, which later became the National Geographic Institute. By means of geodesy and these points accurate maps could be drawn up. Source Wikipedia