The Hofmolen
At the Voorde, where the Hollebeek and the Woluwe meet, stood the Hofmolen (court mill), so called because it depended on the old manor of Diegem. On 18 August 1338 Ghislenus Taye paid quit-rent for it; other members of the Taye family followed. In 1394 the mill belonged to Sir Jan van Diedeghem, lord of Diegem, and Jan de Cuypere worked there as an oil miller.
On 20 July 1411 Jan die Hertoge of Diedegem made an agreement with the Duke of Brabant's steward: among other things he was allowed to dig two channels to bring water from the Woluwe into his moat, and to put a gate on the road to his mill, provided it stayed unlocked so that everyone could pass freely. He had a mill house built and in 1439 turned the oil mill into a malt and corn mill.
In 1478 Hendrick van Ertynghen, landlord of the Red Shield inn in Brussels, owned the Hofmolen and the nearby Poeselmolen. Because the two mills hindered each other, through silting and the damming of the water, he was allowed in 1479 to pull down the Poeselmolen and rebuild it further downstream as a paper mill. In 1497 he was given permission to make paper at the Hofmolen as well.
Henry de la Gruse
In the 16th century the mill passed to Henry de la Gruse, the leader of the Calvinists in the area of Diegem, Melsbroek and Machelen. He played a leading part in the mill war with Vilvoorde. On 13 September 1568 the Council of Troubles banished him; his house, orchard, water-powered corn mill and lands were seized and sold at auction.
The Grooten Molen
At the end of the 16th century the name Hofmolen disappears from the sources. In 1748 a new name appears: den Grooten Molen binnen Dieghem (the big mill in Diegem), as it is also marked on the Ferraris map of 1777. In the first half of the 19th century the corn miller Petrus Moonens owned it, then his widow Elisabeth Stuckens, who died in 1860. From 1864 Jan Frans De Bontridder ran the mill.
In 1902 the De Bontridder family sold the mill to August Ulric Marga, the new occupant of the castle. He used the water wheel to generate electricity for his cartridge factory and, through a thick cable, for the Refragor hall on the Haachtsesteenweg, where the first film shows in Diegem took place. Shortly afterwards the mill disappeared.